Gauge blocks
Encyclopedia
A gauge block is a precision ground and lapped
length
measuring standard. Invented in 1896 by Swedish machinist Carl Edvard Johansson
, they are used as a reference for the calibration of measuring equipment used in machine shops, such as micrometers, sine bar
s, calipers, and dial indicators (when used in an inspection role
). Gauge blocks are the main means of length standardization used by industry.
or chromium carbide
because it is harder and wears less. Gauge blocks come in sets of blocks of various lengths, along with two wear blocks, to allow a wide variety of standard lengths to be made up by stacking them. The length of each block is actually slightly shorter than the nominal length stamped on it, because the stamped length includes the length of one wring film, a film of lubricant which separates adjacent block faces in normal use. This nominal length is known as the interferometric length.
In use, the blocks are removed from the set, cleaned of their protective coating (petroleum jelly
or oil) and wrung together to form a stack of the required dimension, with the minimum number of blocks. Gauge blocks are calibrated to be accurate at 68 °F (20 °C) and should be kept at this temperature when taking measurements. This mitigates the effects of thermal expansion
. The wear blocks, made of a harder substance like tungsten carbide
, are included at each end of the stack, whenever possible, to protect the gauge blocks from being damaged in use.
It is believed that the last two sources are the most significant.
The process of wringing involves four steps:
After use the blocks are re-oiled or greased to protect against corrosion
.
The ability for a given gauge block to wring is called ; it is officially defined as "the ability of two surfaces to adhere tightly to each other in the absence of external means." The minimum conditions for wringability are a surface finish
of 1 uin AA or better, and a flatness
of at least 5 uin.
There is a formal test to measure wringability. First, the block is prepared for wringing using the standard process. The block is then slid across a 2 in (50.8 mm) reference grade (1 uin flatness) quartz optical flat while applying moderate pressure. Then, the bottom of the gauge block is observed (through the optical flat) for oil or color. For Federal Grades 0.5, 1, and 2 and ISO grades K, 00, and 0 no oil or color should be visible under the gauge block. For Federal Grade 3 and ISO grades 1 and 2, no more than 20% of the surface area should show oil or color. Note that this test is hard to perform on gauge blocks thinner than 0.1 in (2.5 mm) because they tend not to be flat in the relaxed state.
Slip gauges are made from a select grade of carbide
with hardness of 1500 Vickers hardness. Long series slip gauges are made from high quality steel having cross section (35 x 9 mm) with holes for clamping two slips together.
A gauge block stone is used to remove nicks and burrs to maintain wringability.
There are two wringing pads used to prepare a gauge block for wringing. The first is an oil pad, which applies a light layer of oil to the block. The second is a dry pad, which removes any excess oil from the block after the oil pad has been used.
More recent grade designations include (U.S. Federal Specification GGG-G-15C):
and ANSI/ASME B89.1.9M, which defines both absolute deviations from nominal dimensions and parallelism limits as criteria for grade determination. Generally, grades are equivalent to former U.S. Federal grades as follows:
The ANSI/ASME standard follows a similar philosophy as set forth in ISO 3650. See the NIST reference below for more detailed information on tolerances for each grade and block size. Also consult page 2 of: Commercial Gauge Block Tolerances (Length refers to the calibrated thickness)
inventor Carl Edvard Johansson
. Johansson was employed in 1888 as an armourer inspector by the state arsenal
Carl Gustafs stads Gevärsfaktori [Carl Gustaf Stad's Rifle Factory] in the town of Eskilstuna
, Sweden. He was concerned with the expensive tools for measuring parts for the Remington
rifles then in production under license at Carl Gustaf. When Sweden adopted a tailored variant of the Mauser carbine
in 1894, Johansson was very excited about the chance to study Mauser's methods of measuring, in preparation for production under license at Carl Gustaf (which began several years later). However, a visit to the Mauser factory in Oberndorf am Neckar
, Germany, turned out to be a disappointment. On the train home, he thought about the problem, and he came up with the idea of a set of blocks that could be combined to make up any measure.
There had already been a long history of increasing use of gauges up to this time, such as gauges for filing and go/no go gauges, which were custom-made individually in a toolroom for use on the shop floor; but there had never been super-precision gauge blocks that could be wrung together to make up different lengths, as Johansson now envisioned.
Back home, Johansson converted his wife's Singer sewing machine to a grinding and lapping machine. He preferred to carry out this precision work at home, as the grinding machines at the rifle factory were not good enough. His wife, Margareta, helped him a lot with the grinding besides the household work. Once Johansson had demonstrated his set at Carl Gustaf, his employer provided time and resources for him to develop the idea. Johansson was granted his first Swedish patent on 2 May 1901, SE patent No. 17017, called "Gauge Block Sets for Precision Measurement". Johansson formed the Swedish company CE Johansson AB (also known as 'CEJ') on 16 March 1917.
Johansson spent many years in America; during his life he crossed the Atlantic 22 times. The first CEJ gauge block set in America was sold to Henry M. Leland
at the Cadillac Automobile Company around 1908. The first manufacturing plant in America for his gauge block sets was established in Poughkeepsie
, Dutchess County, New York, in 1919. The economic environment of the post–World War I recession and depression of 1920–21 did not turn out so well for the company, so in 1923 he wrote a letter to Henry Ford
of the Ford Motor Company
, where he proposed a cooperation in order to save his company. Henry Ford became interested, and on 18 November 1923 he began working for Henry Ford in Dearborn, Michigan
. Hounshell (1984), citing Althin (1948) and various archive primary sources, says, "Henry Ford purchased the famous gaugemaking operation of the Swede C. E. Johansson in 1923 and soon moved it into the laboratory facility in Dearborn. Between 1923 and 1927, the Johansson division supplied 'Jo-blocks' to the Ford toolroom
and any manufacturer who could afford them. It also made some of the Ford 'go' and 'no-go' gauges used in production as well as other precision production devices."
In 1936, at the age of 72, Johansson felt it was time to retire and go back to Sweden. He was awarded the large gold medal of the Royal Swedish Academy of Engineering Sciences
in 1943, shortly after his death.
s or similar applications.
Lapping
Lapping is a machining operation, in which two surfaces are rubbed together with an abrasive between them, by hand movement or by way of a machine.This can take two forms...
length
Length
In geometric measurements, length most commonly refers to the longest dimension of an object.In certain contexts, the term "length" is reserved for a certain dimension of an object along which the length is measured. For example it is possible to cut a length of a wire which is shorter than wire...
measuring standard. Invented in 1896 by Swedish machinist Carl Edvard Johansson
Carl Edvard Johansson
Carl Edvard Johansson was a Swedish inventor and scientist.Johansson invented the gauge block set, also known as "Jo Blocks" . He was granted his first Swedish patent on 2 May 1901, Swedish patent No. 17017 called "Gauge Block Sets for Precision Measurement". He formed the Swedish company CE...
, they are used as a reference for the calibration of measuring equipment used in machine shops, such as micrometers, sine bar
Sine bar
It consists of a hardened, precision ground body with two precision ground cylinders fixed at the ends. The distance between the centers of the cylinders is precisely controlled, and the top of the bar is parallel to a line through the centers of the two rollers...
s, calipers, and dial indicators (when used in an inspection role
Quality control
Quality control, or QC for short, is a process by which entities review the quality of all factors involved in production. This approach places an emphasis on three aspects:...
). Gauge blocks are the main means of length standardization used by industry.
Description
Each gauge block consists of a block of metal or ceramic with two opposing faces ground precisely flat and parallel, a precise distance apart. Standard grade blocks are made of a hardened steel alloy, while calibration grade blocks are often made of tungsten carbideTungsten carbide
Tungsten carbide is an inorganic chemical compound containing equal parts of tungsten and carbon atoms. Colloquially, tungsten carbide is often simply called carbide. In its most basic form, it is a fine gray powder, but it can be pressed and formed into shapes for use in industrial machinery,...
or chromium carbide
Chromium carbide
Chromium carbide is an extremely hard refractory ceramic material. It is usually processed by sintering. It has the appearance of a gray powder with orthorhombic crystal structure. The orthorhombic Cr3C2 occurs extremely rarely as mineral tongbaite....
because it is harder and wears less. Gauge blocks come in sets of blocks of various lengths, along with two wear blocks, to allow a wide variety of standard lengths to be made up by stacking them. The length of each block is actually slightly shorter than the nominal length stamped on it, because the stamped length includes the length of one wring film, a film of lubricant which separates adjacent block faces in normal use. This nominal length is known as the interferometric length.
In use, the blocks are removed from the set, cleaned of their protective coating (petroleum jelly
Petroleum jelly
Petroleum jelly, petrolatum, white petrolatum or soft paraffin, CAS number 8009-03-8, is a semi-solid mixture of hydrocarbons , originally promoted as a topical ointment for its healing properties...
or oil) and wrung together to form a stack of the required dimension, with the minimum number of blocks. Gauge blocks are calibrated to be accurate at 68 °F (20 °C) and should be kept at this temperature when taking measurements. This mitigates the effects of thermal expansion
Thermal expansion
Thermal expansion is the tendency of matter to change in volume in response to a change in temperature.When a substance is heated, its particles begin moving more and thus usually maintain a greater average separation. Materials which contract with increasing temperature are rare; this effect is...
. The wear blocks, made of a harder substance like tungsten carbide
Tungsten carbide
Tungsten carbide is an inorganic chemical compound containing equal parts of tungsten and carbon atoms. Colloquially, tungsten carbide is often simply called carbide. In its most basic form, it is a fine gray powder, but it can be pressed and formed into shapes for use in industrial machinery,...
, are included at each end of the stack, whenever possible, to protect the gauge blocks from being damaged in use.
Wringing
Wringing is the process of sliding two blocks together so that their faces lightly bond. Because of their ultraflat surfaces, when wrung, gauge blocks adhere to each other tightly. Properly wrung blocks may withstand a 75 lbf (333.6 N) pull. While the exact mechanism that causes wringing is unknown, it is believed to be a combination of:- Air pressure applies pressure between the blocks because the air is squeezed out of the joint.
- Surface tensionSurface tensionSurface tension is a property of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects to run on the water surface...
from oil and water vaporWater vaporWater vapor or water vapour , also aqueous vapor, is the gas phase of water. It is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Under typical atmospheric conditions, water vapor is continuously...
that is present between the blocks. - Molecular attractionMolecular attractionMolecular attraction occurs when neutrally-charged molecules nevertheless experience the uneven distribution of electrons over their structure due to London Forces induced by random variations of electron density occurring in non-polar compounds, hydrogen bonding due to the production of what is...
occurs when two very flat surfaces are brought into contact. This force causes gauge blocks to adhere even without surface lubricants, and in a vacuum.
It is believed that the last two sources are the most significant.
The process of wringing involves four steps:
- Wiping a clean gauge block across an oiled pad (see the accessories section).
- Wiping any extra oil off the gauge block using a dry pad (see the accessories section).
- The block is then slid perpendicularly across the other block while applying moderate pressure until they form a cruciform.
- Finally, the block is rotated until it is inline with the other block.
After use the blocks are re-oiled or greased to protect against corrosion
Corrosion
Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen...
.
The ability for a given gauge block to wring is called ; it is officially defined as "the ability of two surfaces to adhere tightly to each other in the absence of external means." The minimum conditions for wringability are a surface finish
Surface finish
Surface finish, also known as surface texture, is the characteristics of a surface. It has three components: lay, surface roughness, and waviness.-Lay:...
of 1 uin AA or better, and a flatness
Flatness
Flatness may refer to:*Flatness *Flatness *Flatness *Flatness *Flatness , a geometrical tolerance required in certain manufacturing situations*Flatness...
of at least 5 uin.
There is a formal test to measure wringability. First, the block is prepared for wringing using the standard process. The block is then slid across a 2 in (50.8 mm) reference grade (1 uin flatness) quartz optical flat while applying moderate pressure. Then, the bottom of the gauge block is observed (through the optical flat) for oil or color. For Federal Grades 0.5, 1, and 2 and ISO grades K, 00, and 0 no oil or color should be visible under the gauge block. For Federal Grade 3 and ISO grades 1 and 2, no more than 20% of the surface area should show oil or color. Note that this test is hard to perform on gauge blocks thinner than 0.1 in (2.5 mm) because they tend not to be flat in the relaxed state.
Accessories
The pictured accessories provide a set of holders and tools to extend the usefulness of the gauge block set. They provide a means of securely clamping large stacks together along with reference points and scribers.Slip gauges are made from a select grade of carbide
Carbide
In chemistry, a carbide is a compound composed of carbon and a less electronegative element. Carbides can be generally classified by chemical bonding type as follows: salt-like, covalent compounds, interstitial compounds, and "intermediate" transition metal carbides...
with hardness of 1500 Vickers hardness. Long series slip gauges are made from high quality steel having cross section (35 x 9 mm) with holes for clamping two slips together.
A gauge block stone is used to remove nicks and burrs to maintain wringability.
There are two wringing pads used to prepare a gauge block for wringing. The first is an oil pad, which applies a light layer of oil to the block. The second is a dry pad, which removes any excess oil from the block after the oil pad has been used.
Grades
They are available in various grades depending on their intended use. Various grading standards include: JIS B 7506-1997 (Japan)/DIN 861-1980 (Germany), ASME (US), BS 4311: Part 1: 1993 (UK). Tolerances will vary within the same grade as the thickness of the material increases.- reference (AAA): small tolerance (±0.05 μm or ±0.000002 in) used to establish standards
- calibration (AA): (tolerance +0.10 μm to −0.05 μm) used to calibrate inspection blocks and very high precision gauging
- inspection (A): (tolerance +0.15 μm to −0.05 μm) used as toolroomToolroomThe term toolroom can refer to three related concepts. The concepts have evolved over the past two centuries as technology itself has evolved.- Storing tools :...
standards for setting other gauging tools - workshop (B): large tolerance (tolerance +0.25 μm to −0.15 μm) used as shop standards for precision measurement
More recent grade designations include (U.S. Federal Specification GGG-G-15C):
- 0.5 — generally equivalent to grade AAA
- 1 — generally equivalent to grade AA
- 2 — generally equivalent to grade A+
- 3 — compromise grade between A and B
and ANSI/ASME B89.1.9M, which defines both absolute deviations from nominal dimensions and parallelism limits as criteria for grade determination. Generally, grades are equivalent to former U.S. Federal grades as follows:
- 00 — generally equivalent to grade 1 (most exacting flatness and accuracy requirements)
- 0 — generally equivalent to grade 2
- AS-1 — generally equivalent to grade 3 (reportedly stands for American Standard - 1)
- AS-2 — generally less accurate than grade 3
- K — generally equivalent to grade 00 flatness (parallelism) with grade AS-1 accuracy
The ANSI/ASME standard follows a similar philosophy as set forth in ISO 3650. See the NIST reference below for more detailed information on tolerances for each grade and block size. Also consult page 2 of: Commercial Gauge Block Tolerances (Length refers to the calibrated thickness)
History
The gauge block set, also known as "Jo Blocks", was developed by the SwedishSweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
inventor Carl Edvard Johansson
Carl Edvard Johansson
Carl Edvard Johansson was a Swedish inventor and scientist.Johansson invented the gauge block set, also known as "Jo Blocks" . He was granted his first Swedish patent on 2 May 1901, Swedish patent No. 17017 called "Gauge Block Sets for Precision Measurement". He formed the Swedish company CE...
. Johansson was employed in 1888 as an armourer inspector by the state arsenal
Arsenal
An arsenal is a place where arms and ammunition are made, maintained and repaired, stored, issued to authorized users, or any combination of those...
Carl Gustafs stads Gevärsfaktori [Carl Gustaf Stad's Rifle Factory] in the town of Eskilstuna
Eskilstuna
Eskilstuna is a city and the seat of Eskilstuna Municipality, Södermanland County, Sweden with 60,185 inhabitants in 2005. Eskilstuna has a large Sweden Finn population....
, Sweden. He was concerned with the expensive tools for measuring parts for the Remington
Remington Arms
Remington Arms Company, Inc. was founded in 1816 by Eliphalet Remington in Ilion, New York, as E. Remington and Sons. It is the oldest company in the United States which still makes its original product, and is the oldest continuously operating manufacturer in North America. It is the only U.S....
rifles then in production under license at Carl Gustaf. When Sweden adopted a tailored variant of the Mauser carbine
Swedish Mauser
"Swedish Mausers" are a family of bolt-action rifles based on an improved variant of Mauser's earlier Model 1893, but using the 6.5x55mm cartridge, and incorporating unique design elements as requested by Sweden. These are the m/94 carbine, m/96 long rifle, m/38 short rifle and m/41 sniper...
in 1894, Johansson was very excited about the chance to study Mauser's methods of measuring, in preparation for production under license at Carl Gustaf (which began several years later). However, a visit to the Mauser factory in Oberndorf am Neckar
Oberndorf am Neckar
Oberndorf am Neckar is a town in the district of Rottweil, in Baden-Württemberg, Germany. It is situated on the river Neckar, 15 km north of Rottweil.-Geography:...
, Germany, turned out to be a disappointment. On the train home, he thought about the problem, and he came up with the idea of a set of blocks that could be combined to make up any measure.
There had already been a long history of increasing use of gauges up to this time, such as gauges for filing and go/no go gauges, which were custom-made individually in a toolroom for use on the shop floor; but there had never been super-precision gauge blocks that could be wrung together to make up different lengths, as Johansson now envisioned.
Back home, Johansson converted his wife's Singer sewing machine to a grinding and lapping machine. He preferred to carry out this precision work at home, as the grinding machines at the rifle factory were not good enough. His wife, Margareta, helped him a lot with the grinding besides the household work. Once Johansson had demonstrated his set at Carl Gustaf, his employer provided time and resources for him to develop the idea. Johansson was granted his first Swedish patent on 2 May 1901, SE patent No. 17017, called "Gauge Block Sets for Precision Measurement". Johansson formed the Swedish company CE Johansson AB (also known as 'CEJ') on 16 March 1917.
Johansson spent many years in America; during his life he crossed the Atlantic 22 times. The first CEJ gauge block set in America was sold to Henry M. Leland
Henry M. Leland
Henry Martyn Leland was a machinist, inventor, engineer and automotive entrepreneur who founded the two premier American luxury marques, Cadillac and Lincoln. Retrieved December 30, 2008....
at the Cadillac Automobile Company around 1908. The first manufacturing plant in America for his gauge block sets was established in Poughkeepsie
Poughkeepsie (city), New York
Poughkeepsie is a city in the state of New York, United States, which serves as the county seat of Dutchess County. Poughkeepsie is located in the Hudson River Valley midway between New York City and Albany...
, Dutchess County, New York, in 1919. The economic environment of the post–World War I recession and depression of 1920–21 did not turn out so well for the company, so in 1923 he wrote a letter to Henry Ford
Henry Ford
Henry Ford was an American industrialist, the founder of the Ford Motor Company, and sponsor of the development of the assembly line technique of mass production. His introduction of the Model T automobile revolutionized transportation and American industry...
of the Ford Motor Company
Ford Motor Company
Ford Motor Company is an American multinational automaker based in Dearborn, Michigan, a suburb of Detroit. The automaker was founded by Henry Ford and incorporated on June 16, 1903. In addition to the Ford and Lincoln brands, Ford also owns a small stake in Mazda in Japan and Aston Martin in the UK...
, where he proposed a cooperation in order to save his company. Henry Ford became interested, and on 18 November 1923 he began working for Henry Ford in Dearborn, Michigan
Dearborn, Michigan
-Economy:Ford Motor Company has its world headquarters in Dearborn. In addition its Dearborn campus contains many research, testing, finance and some production facilities. Ford Land controls the numerous properties owned by Ford including sales and leasing to unrelated businesses such as the...
. Hounshell (1984), citing Althin (1948) and various archive primary sources, says, "Henry Ford purchased the famous gaugemaking operation of the Swede C. E. Johansson in 1923 and soon moved it into the laboratory facility in Dearborn. Between 1923 and 1927, the Johansson division supplied 'Jo-blocks' to the Ford toolroom
Toolroom
The term toolroom can refer to three related concepts. The concepts have evolved over the past two centuries as technology itself has evolved.- Storing tools :...
and any manufacturer who could afford them. It also made some of the Ford 'go' and 'no-go' gauges used in production as well as other precision production devices."
In 1936, at the age of 72, Johansson felt it was time to retire and go back to Sweden. He was awarded the large gold medal of the Royal Swedish Academy of Engineering Sciences
Royal Swedish Academy of Engineering Sciences
The Royal Swedish Academy of Engineering Sciences or Kungl. Ingenjörsvetenskapsakademien , founded in 1919 by King Gustaf V, is one of the Royal Academies in Sweden...
in 1943, shortly after his death.
Gauge pins
Similar to gauge blocks, these are precision ground cylindrical bars for use in Go-NoGo gaugeGo-NoGo gauge
A Go-NoGo gauge refers to an inspection tool used to check a workpiece against its allowed tolerances. Its name derives from its use: the gauge has two tests; the check involves the workpiece having to pass one test and fail the other .It is an integral part of the quality process that is used...
s or similar applications.
Gauge rollers and balls
These are supplied as sets of individual rollers or balls as used in roller or ball bearingsBearing (mechanical)
A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can...