I see a drawing from a customer that is drawn with a tolerance of 1μ.
Is it possible to actually cut plastic processing with that tolerance? ・・・・・・・
I would like to say that it is possible, but… the answer is no.

Then, why is it possible⁉?
Here, I would like to explain how much the dimensions expand and contract with temperature change.

What is the coefficient of linear expansion?

The coefficient of linear expansion expresses the rate at which the length of an object changes (expands or contracts) due to changes in temperature.
The rate of change in length is called the coefficient of linear expansion, and the rate of change in volume is called the coefficient of volumetric expansion.
To put it crudely, the coefficient of linear expansion is a numerical expression of the change in temperature of 1°C, which varies depending on the material even in the same temperature environment.

Reference values
UHMW-PE: 20 to 10
PTFE 14 to 12
MC nylon 11～6.5
POM 9
Unit: (×10E-5/℃)　　　　

For comparison, the values for metals are also shown. (Only some of them)

Iron 11.8
Aluminum 23.1
Unit: (×10E-6/℃)

It is difficult to understand from the numerical values alone, but the coefficient of expansion differs by one order of magnitude between metals and plastics.
In other words, the dimensional change of plastic is that much larger.

Now, let’s apply the actual formula and convert it into numbers.
The following formula can be used to calculate the value.

2. Calculation Formula

Material linear expansion coefficient x 10-⁵ x product dimensions x temperature change

Example: In the case of UHMW-PE with a coefficient of linear expansion of 20

20 x 0.00001 x 100 (product dimensions) = 0.020 mm
The above is the dimensional change of 1°C.

In case of 10°C change 0.019×10°C＝0.20㎜

*This should be considered as a rough guide only, as there are differences depending on the product dimensions and temperature range.

What do you think?
It is clear that UHMW-PE expands by 0.2 mm with a change in temperature of 10°C.
It is easier to understand when you actually see it in figures.

3. Summary

Not all materials show this kind of change,
Compared to metals, plastics are more sensitive to temperature changes.
We can also make the desired values closer with the know-how of our technicians.
Please contact us once if you have any questions regarding accuracy.

Translated with DeepL.com (free version)