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Drawing sheet for a POM gear

Question asked by Eg Gloo on Mar 27, 2017
Latest reply on Mar 28, 2017 by Dennis Dohogne

Hi all,

 

I'm trying to design a 28 teeth POM gear for an education project. We'll need about 3,000 units, so we decided injection moulding is probably the best way to go. I have several questions:

 

1) The injection moulder's draft angle is 4 degrees - is it too big for POM gears?

 

2) I have produced a drawing sheet, but I can't seem to specify the draft angle. Is it typically acceptable to specify the draft angle as a note?

 

3) Usually, what tolerances are acceptable for POM gears? Is 0.05mm (linear? angular?) too tight?

 

4) Are tolerances usually specified for each dimension or stated as a note on the sheet?

 

5) Are fillets needed around the teeth?

 

Here's the sheet so far:

 

spur gear_am2a.JPG

Does it look adequate for manufacturing?

 

Any help appreciated.

 

**EDIT:**

 

A 4 degree draft angle is too big, so I'll find a manufacturer that can do 0.5 degree.

 

spur gear_am2a.JPG

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