Granite wani nau'in dutse ne mai kama da dutse mai kama da dutse wanda aka haƙa saboda ƙarfinsa, yawansa, juriyarsa, da kuma juriyarsa ga tsatsa. Amma granite kuma yana da amfani sosai - ba wai kawai murabba'ai da murabba'ai ba ne! A gaskiya ma, muna aiki da ƙarfin gwiwa tare da sassan granite waɗanda aka ƙera su da siffofi, kusurwoyi, da lanƙwasa na kowane irin bambanci akai-akai - tare da kyakkyawan sakamako.
Through our state of the art processing, cut surfaces can be exceptionally flat. These qualities make granite the ideal material to create custom-size and custom-design machine bases and metrology components. Granite is:
■ mai iya sarrafa injina
■ daidai lebur idan aka yanke kuma aka gama
■ mai jure tsatsa
■ mai ɗorewa
■ na dogon lokaci
Kayan aikin granite suma suna da sauƙin tsaftacewa. Lokacin ƙirƙirar ƙira na musamman, tabbatar da zaɓar granite don fa'idodinsa mafi girma.

MATAKAN / AIKIN CI GABA DA ƊAUKA
Granite ɗin da ZHHIMG ke amfani da shi don samfuran farantin saman mu na yau da kullun yana da babban abun ciki na quartz, wanda ke ba da juriya ga lalacewa da lalacewa. Launukan Baƙi Masu Kyau suna da ƙarancin shan ruwa, wanda ke rage yuwuwar ma'aunin daidaiton ku yana yin tsatsa yayin da kuke kan faranti. Launin granite da ZHHIMG ke bayarwa yana haifar da ƙarancin haske, wanda ke nufin ƙarancin wahalar ido ga mutanen da ke amfani da faranti. Mun zaɓi nau'ikan granite ɗinmu yayin da muke la'akari da faɗaɗa zafi don ƙoƙarin rage wannan ɓangaren.

CUSTOM APPLICATIONS
Idan aikace-aikacenku ya buƙaci faranti mai siffofi na musamman, abubuwan da aka saka a zare, ramuka ko wasu injina, za ku so ku zaɓi abu kamar Baƙin Jinan. Wannan kayan halitta yana ba da ƙarfi mai kyau, rage girgiza mai kyau, da kuma ingantaccen injin.

Yana da mahimmanci a lura cewa launi kaɗai ba shine alamar yanayin jikin dutsen ba. Gabaɗaya, launin granite yana da alaƙa kai tsaye da kasancewar ko rashin ma'adanai, wanda ƙila ba shi da wani tasiri ga halayen da ke yin kyakkyawan kayan farantin saman. Akwai granites masu launin ruwan hoda, toka, da baƙi waɗanda suka dace da faranti na saman, da kuma granites baƙi, toka, da ruwan hoda waɗanda ba su dace da aikace-aikacen daidai ba. Muhimman halayen granite, kamar yadda suke da alaƙa da amfani da shi azaman kayan farantin saman, ba su da alaƙa da launi, kuma sune kamar haka:
■ Tauri (juyawa a ƙarƙashin kaya - wanda Modulus of Elasticity ya nuna)
■ Taurin kai
■ Yawan yawa
■ Juriyar lalacewa
■ Kwanciyar hankali
■ Rarrabuwa

Mun gwada kayan granite da yawa kuma mun kwatanta waɗannan kayan. A ƙarshe mun sami sakamakon, granite baƙi na Jinan shine mafi kyawun kayan da muka taɓa sani. Granite baƙi na Indiya da granite na Afirka ta Kudu suna kama da Jinan Black Granite, amma halayensu na zahiri ba su kai Jinan Black Granite ba. ZHHIMG zai ci gaba da neman ƙarin kayan granite a duniya kuma ya kwatanta halayensu na zahiri.

Domin ƙarin bayani game da dutse mai daraja wanda ya dace da aikinku, tuntuɓe muinfo@zhhimg.com.

Masana'antun daban-daban suna amfani da ma'auni daban-daban. Akwai ma'auni da yawa a duniya.
DIN Standard, ASME B89.3.7-2013 ko Federal Specification GGG-P-463c (Granite Surface Faranti) da sauransu a matsayin tushen takamaiman bayanan su.

Kuma za mu iya ƙera farantin duba daidaiton dutse bisa ga buƙatunku. Barka da zuwa tuntuɓar mu idan kuna son ƙarin bayani game da ƙarin ƙa'idodi.

Za a iya ɗaukar faɗin faɗin a matsayin dukkan wuraren da ke kan saman da ke cikin layuka biyu masu layi ɗaya, wato matakin tushe da kuma matakin rufin. Ma'aunin nisan da ke tsakanin layukan shine faɗin faɗin saman gaba ɗaya. Wannan ma'aunin faɗin faɗin yawanci yana ɗauke da haƙuri kuma yana iya haɗawa da ayyana matsayi.

Misali, an bayyana juriyar lanƙwasa ga ma'auni uku na yau da kullun a cikin ƙayyadaddun ƙayyadaddun tarayya kamar yadda aka ƙaddara ta hanyar dabara mai zuwa:
■ Matsayin Dakin Gwaji AA = (40 + murabba'i mai kusurwa/25) x .000001" (mai gefe ɗaya)
■ Dubawa A Mataki A = Dakin gwaje-gwaje AA Mataki 2
■ Ɗakin Kayan Aiki Daraja B = Daraja AA x 4.

Ga faranti na saman da aka daidaita, muna ba da garantin jurewar lanƙwasa wanda ya wuce buƙatun wannan ƙayyadaddun bayanai. Baya ga lanƙwasa, ASME B89.3.7-2013 & Bayanin Tarayya GGG-P-463c suna magance batutuwa waɗanda suka haɗa da: daidaiton ma'auni mai maimaitawa, halayen kayan granites na farantin saman, ƙarewar saman, wurin tallafi, tauri, hanyoyin dubawa masu karɓuwa, shigar da abubuwan da aka saka a zare, da sauransu.

Faranti na saman dutse na ZHHIMG da faranti na duba dutse sun cika ko sun wuce duk buƙatun da aka tsara a cikin wannan ƙayyadaddun bayanai. A halin yanzu, babu takamaiman ƙayyadaddun bayanai game da faranti na kusurwa na dutse, daidai gwargwado, ko murabba'ai na farko.

Kuma zaku iya samun dabarun wasu ma'auni a cikinSAUKEWA.

Na farko, yana da mahimmanci a kiyaye tsabtar farantin. Kura mai lalata iska yawanci ita ce babbar hanyar lalacewa da tsagewa a kan farantin, domin yana da alaƙa da sanya kayan aiki da kuma saman taɓawa na ma'aunin. Na biyu, rufe farantin don kare shi daga ƙura da lalacewa. Ana iya tsawaita tsawon lokacin lalacewa ta hanyar rufe farantin lokacin da ba a amfani da shi, ta hanyar juya farantin lokaci-lokaci don kada yanki ɗaya ya yi amfani da shi fiye da kima, da kuma maye gurbin ma'aunin ƙarfe a kan ma'aunin ma'aunin ma'aunin ma'aunin carbide. Haka kuma, a guji sanya abinci ko abubuwan sha masu laushi a kan farantin. Lura cewa yawancin abubuwan sha masu laushi suna ɗauke da sinadarin carbonic ko phosphoric acid, wanda zai iya narkar da ma'adanai masu laushi kuma ya bar ƙananan ramuka a saman.

Wannan ya danganta da yadda ake amfani da farantin. Idan zai yiwu, muna ba da shawarar tsaftace farantin a farkon rana (ko aikin aiki) da kuma a ƙarshe. Idan farantin ya yi ƙazanta, musamman da ruwa mai mai ko mai, wataƙila a tsaftace shi nan da nan.

Tsaftace farantin akai-akai da ruwa ko kuma ZHHIMG mai tsabtace farantin saman ruwa mara ruwa. Zaɓin mafita na tsaftacewa yana da mahimmanci. Idan aka yi amfani da mai narkewa mai canzawa (acetone, lacquer thinner, barasa, da sauransu) tururin zai sanyaya saman, kuma ya ɓata shi. A wannan yanayin, ya zama dole a bar farantin ya daidaita kafin amfani da shi ko kuma kurakurai na aunawa za su faru.

Adadin lokacin da ake buƙata don faranti ya daidaita zai bambanta dangane da girman faranti, da kuma yawan sanyaya. Sa'a ɗaya ya isa ga ƙananan faranti. Ana iya buƙatar sa'o'i biyu ga manyan faranti. Idan aka yi amfani da injin tsabtace ruwa, za a kuma sami ɗan sanyi mai ƙafewa.

Farantin zai kuma riƙe ruwan, kuma wannan na iya haifar da tsatsa ta sassan ƙarfe da suka taɓa saman. Wasu masu tsaftacewa kuma za su bar wani abu mai mannewa bayan sun bushe, wanda zai jawo ƙurar iska, kuma a zahiri zai ƙara lalacewa, maimakon rage shi.

Wannan ya dogara da amfani da farantin da muhallinsa. Muna ba da shawarar cewa sabon farantin ko kayan haɗin granite daidai su sami cikakken gyarawa cikin shekara ɗaya da siyansa. Idan farantin saman granite zai ga amfani mai yawa, yana da kyau a rage wannan tazara zuwa watanni shida. Dubawa na wata-wata don kurakuran aunawa akai-akai ta amfani da matakin lantarki, ko makamancin haka zai nuna duk wani tabo da ke tasowa kuma yana ɗaukar mintuna kaɗan kawai don yin aiki. Bayan an tantance sakamakon sake daidaitawa na farko, ana iya tsawaita tazara ko gajarta kamar yadda tsarin ingancin ciki ya ba da izini ko buƙata.

Za mu iya bayar da sabis don taimaka muku duba da daidaita farantin saman granite ɗinku.

Akwai dalilai da yawa da ke haifar da bambance-bambance tsakanin calibrations:

• An wanke saman da maganin zafi ko sanyi kafin a daidaita shi, kuma ba a ba shi isasshen lokaci don daidaita shi ba
• Farantin ba shi da goyon baya yadda ya kamata
• Canjin yanayin zafi
• Zane-zane
• Hasken rana kai tsaye ko wani zafi mai haske a saman farantin. Tabbatar cewa hasken da ke sama ba ya dumama saman.
• Bambance-bambance a cikin yanayin zafin jiki na tsaye tsakanin hunturu da bazara (Idan zai yiwu, san zafin yanayin yanayin tsayi a lokacin da aka yi ma'aunin.)
• Farantin ba a ba da isasshen lokaci don daidaita yanayin bayan jigilar kaya ba
• Amfani da kayan aikin dubawa mara kyau ko amfani da kayan aikin da ba a daidaita su ba
• Canjin saman da ya faru sakamakon lalacewa

Nawa nau'ikan ramuka a kan granite daidai?

Ramummuka akan Daidaitattun Abubuwan Granite

Ga masana'antu da yawa, ɗakunan dubawa da dakunan gwaje-gwaje, ana dogara da faranti na dutse masu daidaito a matsayin tushen aunawa daidai. Saboda kowace ma'auni ta layi ta dogara ne akan madaidaicin saman tunani wanda daga ciki ake ɗaukar ma'auni na ƙarshe, faranti na saman suna ba da mafi kyawun matakin tunani don duba aiki da tsara shi kafin a yi aiki. Hakanan su ne tushen da suka dace don yin ma'aunin tsayi da saman aunawa. Bugu da ƙari, babban matakin lanƙwasa, kwanciyar hankali, inganci gabaɗaya da aikin yi ya sa su zama kyakkyawan zaɓi don hawa tsarin aunawa na injiniya, lantarki da na gani mai zurfi. Ga kowane ɗayan waɗannan hanyoyin aunawa, yana da mahimmanci a kiyaye faranti na saman daidaitacce.

Repeat Measurements and Flatness

Ma'aunin lanƙwasa da maimaitawa suna da matuƙar muhimmanci don tabbatar da daidaiton saman. Za a iya ɗaukar lanƙwasa a matsayin dukkan maki a saman da ke cikin layuka biyu masu layi ɗaya, matakin tushe da kuma matakin rufin. Ma'aunin nisan da ke tsakanin jiragen shine cikakken lanƙwasa na saman. Wannan ma'aunin lanƙwasa yawanci yana ɗauke da haƙuri kuma yana iya haɗawa da ayyana maki.

The flatness tolerances for three standard grades are defined in the federal specification as determined by the following formula:

DIN Standard, GB Standard, ASME Standard, JJS Standard... ƙasa daban-daban tare da matsayi daban-daban...

Ƙarin bayani game da Standard.

In addition to flatness, repeatability must be ensured. A repeat measurement is a measurement of local flatness areas. It is a measurement taken anywhere on the surface of a plate that will repeat within the stated tolerance. Controlling local area flatness to a tighter tolerance than overall flatness guarantees a gradual change in surface flatness profile, thereby minimizing local errors.

Domin tabbatar da cewa farantin saman ya dace da ƙayyadaddun ma'auni na lanƙwasa da maimaitawa, masana'antun faranti na saman dutse ya kamata su yi amfani da Bayanin Tarayya GGG-P-463c a matsayin tushen ƙayyadaddun su. Wannan ma'auni yana magance daidaiton ma'auni mai maimaitawa, halayen kayan granite na farantin saman, ƙarewar saman, wurin tallafi, tauri, hanyoyin dubawa da shigarwa na zare masu dacewa.

Checking Plate Accuracy

Ta hanyar bin wasu ƙa'idodi masu sauƙi, saka hannun jari a cikin farantin saman dutse ya kamata ya daɗe na tsawon shekaru. Dangane da amfani da farantin, yanayin shago da kuma daidaiton da ake buƙata, yawan duba daidaiton farantin saman ya bambanta. Babban ƙa'ida ita ce sabon farantin ya sami cikakken gyarawa cikin shekara ɗaya da siyan sa. Idan ana amfani da farantin akai-akai, yana da kyau a rage wannan lokacin zuwa watanni shida.

Before a surface plate has worn beyond specification for overall flatness, it will show worn or wavy posts. Monthly inspection for repeat measurement errors using a repeat reading gage will identify wear spots. A repeat reading gage is a high-precision instrument that detects local error and can be displayed on a high magnification electronic amplifier.

An effective inspection program should include regular checks with an autocollimator, providing actual calibration of overall flatness traceable to National Institute of Standards and Technology (NIST). Comprehensive calibration by the manufacturer or an independent company is necessary from time to time.

Variations Between Calibrations

A wasu lokuta, akwai bambance-bambance tsakanin daidaita farantin saman. Wani lokaci abubuwa kamar canjin saman da ya samo asali daga lalacewa, rashin amfani da kayan aikin dubawa daidai ko amfani da kayan aikin da ba a daidaita ba na iya haifar da waɗannan bambance-bambancen. Duk da haka, abubuwa biyu da suka fi yawa sune zafin jiki da tallafi.

One of the most important variables is temperature. For instance, the surface might have been washed with a hot or cold solution prior to calibration and not allowed sufficient time to normalize. Other causes of temperature change include drafts of cold or hot air, direct sunlight, overhead lighting or other sources of radiant heat on the surface of the plate.

There also can be variations in the vertical temperature gradient between winter and summer. In some cases, the plate is not allowed sufficient time to normalize after shipment. It is a good idea to record the vertical gradient temperature at the time the calibration is performed.

Another common cause for calibration variation is a plate that is improperly supported. A surface plate should be supported at three points, ideally located 20% of the length in from the ends of the plate. Two supports should be located 20% of the width in from the long sides, and the remaining support should be centered.

Only three points can rest solidly on anything but a precision surface. Attempting to support the plate at more than three points will cause the plate to receive its support from various combinations of three points, which will not be the same three points on which it was supported during production. This will introduce errors as the plate deflects to conform to the new support arrangement. Consider using steel stands with support beams designed to line up with the proper support points. Stands for this purpose are generally available from the surface plate manufacturer.

If the plate is properly supported, precise leveling is only necessary if an application specifies it. Leveling is not necessary to maintain the accuracy of a properly supported plate.

Extend Plate Life

Bin wasu ƙa'idodi zai rage lalacewa a kan farantin saman dutse kuma a ƙarshe, zai tsawaita rayuwarsa.

Da farko, yana da mahimmanci a kiyaye faranti mai tsafta. Kura mai gogewa daga iska yawanci ita ce babbar hanyar lalacewa da tsagewa a kan faranti, domin yana da alaƙa da kayan aiki da kuma saman ma'aunin da ke taɓawa.

It also is important to cover plates to protect it from dust and damage. Wear life can be extended by covering the plate when not in use.

A juya farantin lokaci-lokaci don kada a yi amfani da shi fiye da kima a wuri ɗaya. Haka kuma, ana ba da shawarar a maye gurbin murfin ƙarfe da faifan carbide a kan ma'aunin.

Avoid setting food or soft drinks on the plate. Many soft drinks contain either carbonic or phosphoric acid, which can dissolve the softer minerals and leave small pits in the surface.

Where to Relap

Idan farantin saman dutse yana buƙatar sake fasalinsa, yi la'akari da ko za a yi wannan aikin a wurin ko a wurin daidaitawa. Ya fi kyau a sake haɗa farantin a masana'anta ko wani wuri na musamman. Amma, idan farantin bai yi laushi sosai ba, yawanci a cikin inci 0.001 na juriyar da ake buƙata, za a iya sake haɗa shi a wurin. Idan farantin ya yi laushi har ya wuce inci 0.001 ba tare da juriya ba, ko kuma idan ya yi rauni ko ya yi rauni sosai, to ya kamata a aika shi zuwa masana'anta don niƙa kafin a sake haɗa shi.

A calibration facility has the equipment and factory setting providing the optimum conditions for proper plate calibration and rework if necessary.

Ya kamata a yi taka tsantsan wajen zaɓar ƙwararren masani kan gyaran fuska da gyaran fuska a wurin. Nemi izini kuma a tabbatar da cewa kayan aikin da ma'aikacin zai yi amfani da su suna da ma'aunin da za a iya ganowa. Kwarewa kuma muhimmin abu ne, domin yana ɗaukar shekaru da yawa kafin a koyi yadda ake daidaita ma'aunin dutse daidai.

Critical measurements start with a precision granite surface plate as a baseline. By ensuring a reliable reference by using a properly calibrated surface plate, manufacturers have one of the essential tools for reliable measurements and better quality parts.Q

Checklist for Calibration Variations

1. An wanke saman da ruwan zafi ko sanyi kafin a daidaita shi kuma ba a ba shi isasshen lokaci don daidaita shi ba.

2. Farantin ba a tallafa masa yadda ya kamata ba.

3. Sauyin yanayin zafi.

4. Zane-zane.

5. Hasken rana kai tsaye ko wani zafi mai haske a saman farantin. Tabbatar cewa hasken da ke sama ba ya dumama saman.

6. Bambancin yanayin zafin jiki tsakanin hunturu da bazara. Idan zai yiwu, san zafin yanayin zafin jiki a tsaye a lokacin da aka yi gyaran.

7. Faranti bai ba da isasshen lokaci don daidaita yanayin bayan jigilar kaya ba.

8. Amfani da kayan aikin dubawa mara kyau ko amfani da kayan aikin da ba a daidaita su ba.

9. Canjin yanayi sakamakon lalacewa.

Tech Tips

• Domin kowace ma'auni ta layi ta dogara ne akan madaidaicin saman tunani wanda daga ciki ake ɗaukar ma'auni na ƙarshe, faranti na saman suna ba da mafi kyawun tsarin tunani don duba aiki da tsara shi kafin a yi aiki.
• Controlling local area flatness to a tighter tolerance than overall flatness guarantees a gradual change in surface flatness profile, thereby minimizing local errors.
• Shirin dubawa mai inganci ya kamata ya haɗa da duba akai-akai tare da na'urar sarrafa iska ta atomatik, wanda ke samar da ainihin daidaiton lanƙwasa da za a iya ganowa ga Hukumar Kula da Inshorar Ƙasa.

Daga cikin ƙwayoyin ma'adinai da suka samar da granite, fiye da kashi 90% na su ne feldspar da quartz, waɗanda feldspar ya fi yawa. Feldspar galibi fari ne, launin toka, kuma ja ne na nama, kuma quartz galibi fari ne mara launi ko launin toka, wanda shine asalin launin granite. Feldspar da quartz ma'adanai ne masu tauri, kuma yana da wuya a motsa da wuka ta ƙarfe. Dangane da ɗigon duhu a cikin granite, galibi baƙi mica, akwai wasu ma'adanai. Kodayake biotite yana da laushi kaɗan, ikonsa na tsayayya da damuwa ba shi da rauni, kuma a lokaci guda suna da ƙaramin adadin granite, sau da yawa ƙasa da 10%. Wannan shine yanayin kayan da granite yake da ƙarfi musamman.

Wani dalili kuma da ya sa granite yake da ƙarfi shi ne cewa ƙwayoyin ma'adinansa suna daure sosai da juna kuma suna cikin juna. Sau da yawa ramukan suna ƙasa da kashi 1% na jimlar girman dutsen. Wannan yana ba granite ikon jure matsin lamba mai ƙarfi kuma danshi ba ya shiga cikin sauƙi.

An yi sassan granite da dutse ba tare da tsatsa ba, juriya ga acid da alkali, juriya mai kyau ga lalacewa da tsawon rai, babu kulawa ta musamman. Ana amfani da sassan daidaito na granite galibi a cikin kayan aikin masana'antar injina. Saboda haka, ana kiran su sassan daidaito na granite ko sassan granite. Halayen sassan daidaito na granite iri ɗaya ne da na dandamalin granite. Gabatarwa ga kayan aiki da auna sassan daidaito na granite: Fasahar injina ta daidai da fasahar injina ta ƙananan hanyoyi ne masu mahimmanci na ci gaba a masana'antar kera injina, kuma sun zama muhimmiyar alama don auna matakin fasaha mai zurfi. Ci gaban fasahar zamani da masana'antar tsaro ba za a iya raba su da fasahar injina ta daidai da fasahar injina ta ƙananan ba. Ana iya zame sassan granite cikin sauƙi a cikin ma'auni, ba tare da tsayawa ba. Ma'aunin saman aiki, ƙagaggun gabaɗaya ba sa shafar daidaiton ma'auni. Ana buƙatar tsara sassan granite kuma a samar da su bisa ga buƙatun ɓangaren buƙata.

Filin aikace-aikacen:

Kamar yadda muka sani, ƙarin injuna da kayan aiki suna zaɓar daidaitattun abubuwan da aka gyara na dutse.

Ana amfani da sassan granite don motsi mai motsi, injinan layi, cmm, cnc, injin laser...

Barka da zuwa tuntube mu don ƙarin bayani.

An yi na'urorin auna dutse da kayan aikin injiniya na granite da babban dutse mai launin Jinan. Saboda daidaiton su, tsawon lokaci, kyakkyawan kwanciyar hankali da juriyar tsatsa, ana ƙara amfani da su wajen duba kayayyaki a masana'antar zamani da kuma fannoni kamar sararin samaniya da binciken kimiyya.

Fa'idodi

-----Tauri sau biyu kamar ƙarfe mai siminti;

-----Ƙarancin canje-canje na girma yana faruwa ne saboda canjin yanayin zafi;

----Ba a samun matsala, don haka babu katsewar aiki;

----Ba ya dauke da burrs ko protrusions saboda tsarin hatsi mai kyau da kuma rashin mannewa sosai, wanda ke tabbatar da babban matakin lanƙwasa a tsawon tsawon rai kuma ba ya haifar da lalacewa ga wasu sassa ko kayan aiki;

----Aiki mara matsala don amfani da kayan maganadisu;

---- Tsawon rai da kuma rashin tsatsa, wanda hakan ke haifar da ƙarancin kuɗin kulawa.

An daidaita faranti na saman dutse daidai gwargwado zuwa babban matakin lanƙwasa don cimma daidaito kuma ana amfani da su azaman tushe don hawa tsarin ma'aunin injiniya, lantarki da na gani mai inganci.

Wasu daga cikin siffofi na musamman na farantin saman granite:

Daidaito a cikin Tauri;

Daidai a ƙarƙashin kaya Yanayi;

Mai Shafar Girgiza;

Mai sauƙin tsaftacewa;

Mai juriya ga naɗewa;

Ƙananan Porosity;

Ba ya gogewa;

Ba Mai Maganadisu ba

Abũbuwan amfãni na Farantin Dutse

First, the rock after a long period of natural aging, uniform structure, coefficient minimum, the internal stress completely disappear, not deformed, so the precision is high.

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Precision Granite Base Can Improve Machine Tool Performances

Requirements are constantly increasing in mechanical engineering in general and in machine tool construction in particular. Achieving maximum precision and performance values without increasing costs are constant challenges to being competitive. The machine tool bed is a decisive factor here. Therefore, more and more machine tool manufacturers are relying on granite. Due to its physical parameters, it offers clear advantages that cannot be achieved with steel or polymer concrete.

Granite is a so-called volcanic deep rock and has a very dense and homogeneous structure with an extremely low coefficient of expansion, low thermal conductivity and high vibration damping.

Below you will discover why the common opinion that granite is mainly only suitable as machine base for high-end coordinate measuring machines is long outdated and why this natural material as a machine tool base is a very advantageous alternative to steel or cast iron even for high-precision machine tools.

We can manufacture granite components for dynamic motion, granite components for linear motors, granite components for ndt, granite components for xray, granite components for cmm, granite components for cnc, granite precision for laser, granite components for aerospace, granite components for precision stages...

High Added Value Without Additional Costs
The increasing use of granite in mechanical engineering is not so much due to the massive increase in the price of steel. Rather, it is because the added value for the machine tool achieved with a machine bed made of granite is possible at very little or no extra cost. This is proven by cost comparisons of well-known machine tool manufacturers in Germany and Europe.

The considerable gain in thermodynamic stability, vibration damping and long-term precision made possible by granite cannot be achieved with a cast iron or steel bed, or only at relatively high cost. For example, thermal errors can account for up to 75% of the total error of a machine, with compensation often attempted for by software – with moderate success. Due to its low thermal conductivity, granite is the better foundation for long-term precision.

With a tolerance of 1 μm, granite easily meets the flatness requirements according to DIN 876 for the degree of accuracy 00. With a value of 6 on the hardness scale 1 to 10, it is extremely hard, and with its specific weight of 2.8g/cm³ it almost reaches the value of aluminium. This also results in additional advantages such as higher feed rates, higher axis accelerations and an extension of the tool life for cutting machine tools. Thus, the change from a cast bed to a granite machine bed moves the machine tool in question into the high-end class in terms of precision and performance – at no extra cost.

Granite’s Improved Ecological Footprint
In contrast to materials such as steel or cast iron, natural stone does not have to be produced with a great deal of energy and using additives. Only relatively small amounts of energy are required for quarrying and surface treatment. This results in a superior ecological footprint, which even at the end of a machine’s life surpasses that of steel as a material. The granite bed can be the basis for a new machine or be used for completely different purposes such as shredding for road construction.

Nor are there any shortages of resources for granite. It is a deep rock formed from magma within the earth’s crust. It has ‘matured’ for millions of years and is available in very large quantities as a natural resource on almost all continents, including all of Europe.

Conclusion: The numerous demonstrable advantages of granite compared to steel or cast iron justify the increasing willingness of mechanical engineers to use this natural material as a foundation for high-precision, high-performance machine tools. Detailed information about granite properties, which are advantageous for machine tools and mechanical engineering, can be found in this further article.

A repeat measurement is a measurement of local flatness areas. The Repeat Measurement specification states that a measurement taken anywhere on the surface of a plate will repeat within the stated tolerance. Controlling local area flatness tighter than overall flatness guarantees a gradual change in surface flatness profile thereby minimizing local errors.

Most manufacturers, including imported brands, adhere to the Federal Specification of overall flatness tolerances but many overlook the repeat measurements. Many of the low value or budget plates available in the market today will not guarantee repeat measurements. A manufacturer who does not guarantee repeat measurements is NOT producing plates that meet the requirements of ASME B89.3.7-2013 or Federal Specification GGG-P-463c, or DIN 876, GB, JJS...

Both are critical to ensure a precision surface for accurate measurements. Flatness specification alone is not sufficient to guarantee measurement accuracy. Take as an example, a 36 X 48 Inspection Grade A surface plate, which meets ONLY the flatness specification of .000300". If the piece being checked bridges several peaks, and the gage being used is in a low spot, the measurement error could be the full tolerance in one area, 000300"! Actually, it can be much higher if the gage is resting on the slope of an incline.

Errors of .000600"-.000800" are possible, depending upon the severity of the slope, and the arm length of the gage being used. If this plate had a Repeat Measurement specification of .000050"F.I.R. then the measurement error would be less than .000050" regardless of where the measurement is taken on the plate. Another problem, which usually arises when an untrained technician attempts to resurface a plate on-site, is the use of Repeat Measurements alone to certify a plate.

The instruments that are used to verify repeatability are NOT designed to check overall flatness. When set to zero on a perfectly curved surface, they will continue to read zero, whether that surface is perfectly flat or perfectly concave or convex 1/2"! They simply verify the uniformity of the surface, not the flatness. Only a plate that meets both the flatness specification AND the repeat measurement specification truly meets the requirements of ASME B89.3.7-2013  or Federal Specification GGG-P-463c.

Ask us about or flatness specification and repeat measurement promise by calling +86 19969991659 or emailing INFO@ZHHIMG.COM

Yes, but they can only be guaranteed for a specific vertical temperature gradient. The effects of thermal expansion on the plate could easily cause a change in accuracy greater than the tolerance if there is a change in the gradient. In some cases, if the tolerance is tight enough, the heat absorbed from overhead lighting can cause enough of a gradient change over several hours.

Granite has a coefficient of thermal expansion of approximately .0000035 inches per inch per 1°F. As an example: A 36" x 48" x 8" surface plate has an accuracy of .000075" (1/2 of Grade AA) at a gradient of 0°F, the top and bottom are the same temperature. If the top of the plate warms up to the point where it is 1°F warmer than the bottom, the accuracy would change to .000275" convex ! Therefore, ordering a plate with a tolerance tighter than Laboratory Grade AA should only be considered if there is adequate climate control.

A surface plate should be supported at 3 points, ideally located 20% of the length in from the ends of the plate. Two supports should be located 20% of the width in from the long sides, and the remaining support should be centered. Only 3 points can rest solidly on anything but a precision surface.

The plate should be supported at these points during production, and it should be supported only at these three points while in use. Attempting to support the plate at more than three points will cause the plate to receive its support from various combinations of three points, which will not be the same 3 points on which it was supported during production. This will introduce errors as the plate deflects to conform to the new support arrangement. All zhhimg steel stands have support beams designed to line up with the proper support points.

If the plate is properly supported, precise leveling is only necessary if your application calls for it. Leveling is not necessary to maintain the accuracy of a properly supported plate.

Why Choose Granite for Machine Bases and Metrology Components?

The answer is 'yes' for almost every application. The advantages of granite include: No rust or corrosion, almost immune to warping, no compensating hump when nicked, longer wear life, smoother action, greater precision, virtually non-magnetic, low co-efficient of thermal expansion, and low maintenance cost.

Granite is a type of igneous rock quarried for its extreme strength, density, durability, and resistance to corrosion. But granite is also very versatile– it’s not just for squares and rectangles! In fact, Starrett Tru-Stone confidently works with granite components engineered in shapes, angles, and curves of all variations on a regular basis—with excellent outcomes.

Through our state of the art processing, cut surfaces can be exceptionally flat. These qualities make granite the ideal material to create custom-size and custom-design machine bases and metrology components. Granite is:

machineable
precisely flat when cut and finished
rust resistant
durable
long lasting
Granite components are also easy to clean. When creating custom designs, be sure to choose granite for its superior benefits.

STANDARDS / HIGH WEAR APPLICATIONS
The granite utilized by ZhongHui for our standard surface plate products has high quartz content, which provides greater resistance to wear and damage. Our Superior Black and Crystal Pink colors have low water absorption rates, minimizing the possibility of your precision gages rusting while setting on the plates. The colors of granite offered by ZhongHui result in less glare, which means less eyestrain for individuals using the plates. We have chosen our granite types while considering thermal expansion in an effort to keep this aspect minimal.

CUSTOM APPLICATIONS
When your application calls for a plate with custom shapes, threaded inserts, slots or other machining, you’ll want to select a material like Black Diabase. This natural material offers superior stiffness, excellent vibration dampening, and improved machinability.

Yes, if they are not too badly worn. Our factory setting and equipment allow the optimum conditions for proper plate calibration and rework if necessary. Generally, if a plate is within .001" of the required tolerance, it can be resurfaced on-site. If a plate is worn to the point where it is more than .001" out of tolerance, or if it is badly pitted or nicked, then it will need to be sent to the factory for grinding prior to relapping.

Great care should be exercised in selecting an on-site calibration and resurfacing technician. We urge you to use caution in selecting your calibration service. Ask for accreditation and verify the equipment that the technician will use has a National Inspection Institution traceable calibration. It takes many years to learn how to properly lap precision granite.

ZhongHui provides quick turn-around on calibrations performed in our factory. Send your plates in for calibration if possible. Your quality and reputation depend on the accuracy of your measurement instruments including surface plates!

Our black surface plates have a significantly higher density and are up to three times as stiff. Therefore, a plate made of the black does not need to be as thick as a granite plate of the same size to have equal or greater resistance to deflection. Reduced thickness means less weight and lower shipping costs.

Beware of others who use lower quality black granite in the same thickness. As stated above, properties of granite, like wood or metal, vary by material and color, and is not an accurate predictor of stiffness, hardness, or wear resistance. In fact, many types of black granite and diabase are very soft and not suitable for surface plate applications.

No. The specialized equipment and training necessary to rework these items requires that they be returned to the factory for calibration and rework.

Yes. Ceramic and granite have similar characteristics, and the methods used to calibrate and lap granite can be used with ceramic items as well. Ceramics are more difficult to lap than granite resulting in a higher cost.

Yes, provided that the inserts are recessed below the surface. If steel inserts are flush with, or above the surface plane, they must be spot-faced down before the plate can be lapped. If required, we can provide that service.

Yes. Steel inserts with the desired thread (English or metric) can be epoxy bonded into the plate at the desired locations. ZhongHui uses CNC machines to provide the tightest insert locations within +/- 0.005”. For less critical inserts, our locational tolerance for threaded inserts is ±.060". Other options include steel T-Bars and dovetail slots machined directly into the granite.

Inserts that are properly bonded using high strength epoxy and good workmanship will withstand a great deal of torsional and shear force. In a recent test, using 3/8"-16 threaded inserts, an independent testing laboratory measured the force required to pull an epoxy-bonded insert from a surface plate. Ten plates were tested. Out of these ten, in nine cases, the granite fractured first. The average load at the point of failure was 10,020 lbs. for gray granite and 12,310 lbs. for black. In the single case where an insert pulled free of the plate, the load at the point of failure was 12,990 lbs.! If a work piece forms a bridge across the insert and extreme torque is applied, it is possible to generate enough force to fracture the granite. Partially for this reason, ZhongHui gives guidelines for the maximum safe torque that can be applied the epoxy bonded inserts: https://www.zhhimg.com/standard-thread-inserts-product/

Yes, but only at our factory. At our plant, we can restore almost any plate to 'like-new' condition, usually for less than half the cost of replacing it. Damaged edges can be cosmetically patched, deep grooves, nicks, and pits can be ground out, and the attached supports can be replaced. In addition, we can modify your plate to increase its versatility by adding solid or threaded steel inserts and cutting slots or clamping lips, per your specifications.

Why Choose Granite?
Granite is a type of igneous rock formed in the Earth millions of years ago. The composition of igneous rock contained many minerals such as quartz that is extremely hard and wear-resistant. In addition to hardness and wear resistance granite has approximately half the coefficient of expansion as cast iron. As its volumetric weight is approximately one third that of cast iron, granite is easier to manoeuvre.

For machine bases and metrology components, black granite is the colour most used. Black granite has a higher percentage of quartz than other colours and is, therefore, the hardest wearing.

Granite is cost-effective, and cut surfaces can be exceptionally flat. Not only can it be hand lapped to achieve extremes of accuracy, but re-conditioning can be performed without moving the plate or table off-site. It is entirely a hand lapping operation and generally costs much less than re-conditioning a cast iron alternative.

These qualities make granite the ideal material to create custom-size and custom-design machine bases and metrology components such as the granite surface plate.

ZhongHui produces bespoke granite products that are created to support specific measurement requirements. These bespoke items vary from straight edges to tri squares. Due to the versatile nature of granite, the components can be produced to any size required; they are hard wearing and long-lasting.

Advantages of Granite Surface Plates
The importance of measuring on an even surface was established by British inventor Henry Maudsley in the 1800s. As a machine tool innovator, he determined that consistent production of parts required a solid surface for reliable measurements.

The industrial revolution created a demand for measuring surfaces, so engineering company Crown Windley created manufacturing standards. The standards for surface plates were first set by Crown in 1904 using metal. As the demand and cost for metal increased, alternative materials for the measuring surface were investigated.

In America, monument creator Wallace Herman established that black granite was an excellent surface plate material alternative to metal. As granite is non-magnetic and doesn’t rust, it soon became the preferred measuring surface.

A granite surface plate is an essential investment for laboratories and test facilities. A granite surface plate of 600 x 600 mm can be mounted on a support stand. The stands provide a working height of 34” (0.86m) with five adjustable points for levelling.

For reliable and consistent measurement results, a granite surface plate is crucial. As the surface is a smooth and stable plane, it enables instruments to be carefully manipulated.

The main advantages of granite surface plates are:

• Non-reflective
• Resistant to chemicals and corrosion
• Low coefficient of expansion compared with cart iron so less affected by temperature change
• Naturally rigid and hard-wearing
• The plane of the surface is unaffected if scratched
• Will not rust
• Non-magnetic
• Easy to clean and maintain
• Calibration and resurfacing can be done onsite
• Suitable for drilling for threaded support inserts
• High vibration damping

For many shops, inspection rooms and laboratories, precision granite surface plates are relied on as the basis for accurate measurement. Because every linear measurement depends on an accurate reference surface from which final dimensions are taken, surface plates provide the best reference plane for work inspection and layout prior to machining. They also are ideal bases for making height measurements and gaging surfaces. Further, a high degree of flatness, stability, overall quality and workmanship make them a good choice for mounting sophisticated mechanical, electronic and optical gaging systems. For any of these measurement processes, it is imperative to keep surface plates calibrated.

Repeat Measurements and Flatness
Both flatness and repeat measurements are critical to ensure a precision surface. Flatness can be considered as all points on the surface being contained within two parallel planes, the base plane and the roof plane. The measurement of distance between the planes is the overall flatness of the surface. This flatness measurement commonly carries a tolerance and may include a grade designation.

The flatness tolerances for three standard grades are defined in the federal specification as determined by the following formula:
Laboratory Grade AA = (40 + diagonal² / 25) x 0.000001 inch (unilateral)
Inspection Grade A = Laboratory Grade AA x 2
Tool Room Grade B = Laboratory Grade AA x 4

In addition to flatness, repeatability must be ensured. A repeat measurement is a measurement of local flatness areas. It is a measurement taken anywhere on the surface of a plate that will repeat within the stated tolerance. Controlling local area flatness to a tighter tolerance than overall flatness guarantees a gradual change in surface flatness profile, thereby minimizing local errors.

To ensure a surface plate meets both the flatness and repeat measurement specifications, manufacturers of granite surface plates should use Federal Specification GGG-P-463c as a basis for their specifications. This standard addresses repeat measurement accuracy, material properties of surface plate granites, surface finish, support point location, stiffness, acceptable methods of inspection and installation of threaded inserts.

Before a surface plate has worn beyond specification for overall flatness, it will show worn or wavy posts. Monthly inspection for repeat measurement errors using a repeat reading gage will identify wear spots. A repeat reading gage is a high-precision instrument that detects local error and can be displayed on a high magnification electronic amplifier.

Checking Plate Accuracy
By following a few simple guidelines, an investment in a granite surface plate should last for many years. Depending on plate usage, shop environment and required accuracy, frequency of checking the surface plate accuracy varies. A general rule of thumb is for a new plate to receive a full recalibration within one year of purchase. If the plate is used frequently, it is advisable to shorten this interval to six months.

Before a surface plate has worn beyond specification for overall flatness, it will show worn or wavy posts. Monthly inspection for repeat measurement errors using a repeat reading gage will identify wear spots. A repeat reading gage is a high-precision instrument that detects local error and can be displayed on a high magnification electronic amplifier.

An effective inspection program should include regular checks with an autocollimator, providing actual calibration of overall flatness traceable to National Institute of Standards and Technology (NIST). Comprehensive calibration by the manufacturer or an independent company is necessary from time to time.

Variations Between Calibrations
In some cases, there are variations between surface plate calibrations. Sometimes factors such as surface change resulting from wear, incorrect use of inspection equipment or use of noncalibrated equipment can account for these variations. The two most common factors, however, are temperature and support.

One of the most important variables is temperature. For instance, the surface might have been washed with a hot or cold solution prior to calibration and not allowed sufficient time to normalize. Other causes of temperature change include drafts of cold or hot air, direct sunlight, overhead lighting or other sources of radiant heat on the surface of the plate.

There also can be variations in the vertical temperature gradient between winter and summer. In some cases, the plate is not allowed sufficient time to normalize after shipment. It is a good idea to record the vertical gradient temperature at the time the calibration is performed.

Another common cause for calibration variation is a plate that is improperly supported. A surface plate should be supported at three points, ideally located 20% of the length in from the ends of the plate. Two supports should be located 20% of the width in from the long sides, and the remaining support should be centered.

Only three points can rest solidly on anything but a precision surface. Attempting to support the plate at more than three points will cause the plate to receive its support from various combinations of three points, which will not be the same three points on which it was supported during production. This will introduce errors as the plate deflects to conform to the new support arrangement. Consider using steel stands with support beams designed to line up with the proper support points. Stands for this purpose are generally available from the surface plate manufacturer.

If the plate is properly supported, precise leveling is only necessary if an application specifies it. Leveling is not necessary to maintain the accuracy of a properly supported plate.

It is important to keep the plate clean. Airborne abrasive dust is usually the greatest source of wear and tear on a plate, as it tends to embed in workpieces and the contact surfaces of gages. Cover plates to protect them from dust and damage. Wear life can be extended by covering the plate when not in use.

Extend Plate Life
Following a few guidelines will reduce wear on a granite surface plate and ultimately, extend its life.

First, it is important to keep the plate clean. Airborne abrasive dust is usually the greatest source of wear and tear on a plate, as it tends to embed in workpieces and the contact surfaces of gages.

It also is important to cover plates to protect it from dust and damage. Wear life can be extended by covering the plate when not in use.

Rotate the plate periodically so that a single area does not receive excessive use. Also, it is recommended to replace steel contact pads on gaging with carbide pads.

Avoid setting food or soft drinks on the plate. Many soft drinks contain either carbonic or phosphoric acid, which can dissolve the softer minerals and leave small pits in the surface.

Where to Relap
When a granite surface plate needs re-surfacing, consider whether to have this service performed on-site or at the calibration facility. It is always preferable to have the plate relapped at the factory or a dedicated facility. If, however, the plate is not too badly worn, generally within 0.001 inch of the required tolerance, it can be resurfaced on-site. If a plate is worn to the point where it is more than 0.001 inch out of tolerance, or if it is badly pitted or nicked, then it should be sent to the factory for grinding prior to relapping.

A calibration facility has the equipment and factory setting providing the optimum conditions for proper plate calibration and rework if necessary.

Great care should be exercised in selecting an on-site calibration and resurfacing technician. Ask for accreditation and verify the equipment that the technician will use has a NIST-traceable calibration. Experience also is an important factor, as it takes many years to learn how to correctly lap precision granite.

Critical measurements start with a precision granite surface plate as a baseline. By ensuring a reliable reference by using a properly calibrated surface plate, manufacturers have one of the essential tools for reliable measurements and better quality parts.

Checklist for Calibration Variations

1. The surface was washed with a hot or cold solution prior to calibration and was not allowed sufficient time to normalize.
2. The plate is improperly supported.
3. Temperature change.
4. Drafts.
5. Direct sunlight or other radiant heat on the surface of the plate. Be sure that overhead lighting is not heating the surface.
6. Variations in the vertical temperature gradient between winter and summer. If at all possible, know the vertical gradient temperature at the time the calibration is performed.
7. Plate not allowed sufficient time to normalize after shipment.
8. Improper use of inspection equipment or use of noncalibrated equipment.
9. Surface change resulting from wear.

Tech Tips
Because every linear measurement depends on an accurate reference surface from which final dimensions are taken, surface plates provide the best reference plane for work inspection and layout prior to machining.

Controlling local area flatness to a tighter tolerance than overall flatness guarantees a gradual change in surface flatness profile, thereby minimizing local errors.