Feb 28, 2020
The most accurate mechanical length measurement devices are finger indicators.
They usually have a scale interval of 1 µm.
A lever system transmits the movement of the measuring pin to the pointer via gears and pinions.
This results in no full pointer rotation.
The finger indicator is the most accurate mechanical length measurement device.
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Nov 27, 2018
A mold is usually divided into two sides according to their function.
The side, which is not moving during production is called fixed side.
This side contains the runner system, therefore another common name is “injection side”.
Jul 17, 2019
The pressure of the melt pushes the mold to open due to a too low clamp force.
On the parting line, the mold opens a little and the outcoming melt freezes and a flash remains.
The risk of the flash formation can be reduced by the use of a machine with a higher clamp force or the reduction of the specific pressure in the cavity.
Another reason for flash formation can be the wrong positioning of the touching surfaces at the parting line.
Oct 21, 2019
A flat glass, also known as plan test glass or plane-parallel test glass, is used for testing small flatness deviations.
It is a manual test device with lapped or polished surfaces and a test method based on the interference of light.
A flat glass is a round, high-precision round glass which is fitted with a frame made of plastic or metal.
This is done to protect the glass from fingerprints.
During the test, the glass is slightly pressed onto the test specimen on one side,
whereby a wedge-shaped slit is formed in which the light forms interferences through reflections.
Visible straight stripes appear on flat surfaces, while concave and convex deviations form ring-shaped stripes,
which, however, stand in opposition to each other.
Between the interference fringes, the measuring surface to the glass pane is about 0.27 µm away in white light.
It is suggested to use monochromatic light for better results.
The prerequisite for the use of flat glass is that the surface to be measured reflects sufficient light.
There are flat and spherically curved test tubes which are specified in DIN 58161 Part 1 and Part 2 respectively.
For example, the measuring surfaces of micrometers can be checked for flatness and parallelism with plane glasses.
Quality:
Flat glass on a surface to be tested.
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Dec 9, 2021
To ensure that after manufacturing a surface has a certain distance between two parallel planes, the symbol Flatness is used.
The distance is entered after the symbol.
Flatness is a shape tolerance and describes in which range the most protruding and the most curved area of a surface may be apart.
Quality Assurance: Symbol of tolerated property with 0.06mm required
flatness
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
