Are Delrin Composite gears in motors as good as metal gears? 1

[BreadboardPerson]

Hello, assuming that everything of the three motors are the same except that the gears are made of different materials. The first one is made of Delrin composite gears, the second one is made of metal and plastic gears and the last one is made of metal gears. How are they ranked in terms of strength against wearing down? I suppose metal gears are better than metal+plastic gears. How is Delrin composite ranked? Is it as strong as metal?

 

[drawoh]

BreadboardPerson,

Look up the material specifications on Matweb. Delrin is weaker and it has a lower friction coefficient. You can get glass filled Delrin, which is stronger, and probably not as slippery.

You can make the Delrin gears bigger. Mechanical design is a set of compromises. What do you need to accomplish?

--
JHG

 

[BreadboardPerson]

Hello drawoh,

Thanks for your reply. I am trying to choose among some commercially available motors that can handle heavy loads. One motor uses gears made of Delrin composite. Another motor uses gears made of powered steel alloy. As for the 3rd one, it is a combination of metal and plastic. Is the one that has gears made of powered steel alloy "much" better than the other two? Is it going to be just better or a lot better?

 

[drawoh]

BreadboardPerson,

Are these motors, or gearmotors? If they are gearmotors, they should have specifications on torque, speed and power. You only care about the material of the gears if you have corrosion problems, or out-gassing in space.

--
JHG

 

[BreadboardPerson]

Hello drawoh,

They are gearmotors. I don't want to use motors that wear down quickly under heavy loads. In this case, it is better to choose the one with powered steel alloy gears rather than delrin composite gears?

 

[MikeHalloran]

In general, plastic gears will be quieter than metal gears, and in some circumstances can run without lubrication.

Plastic gears driven by a steel pinion formed on the end of a motor shaft are fairly common.

Delrin's mechanical properties can be improved by reinforcemnt with glass fibers, up to about 30 pct by volume, at some expense in mold life. Teflon fibers can also be substituted for some of the glass, e.g. for friction reduction.

All alloys of Delrin have different shrink factors, so a designer needs to settle on the compounding before the mold is cut. It is not possible to develop a mold for neat plastic and just add stuff to it until the molded article gets strong enough, because the added materials affect the shrinkage and mold flow.

To sort of answer your question,

For gearmotors of identical geometry, sintered steel should be the strongest.
Plastic gears are normally somewhat wider than metal gears, and their teeth may be coarser.

For gearmotors of identical torque/speed rating, the internal geometry may be considerably different because of the disparate properties of the materials and different manufacturing methods. ... as stated above.

To an MBA, something like "Which option is best if I just change the material of a given part or set of parts?" is a perfectly logical question.
To an engineer, it's a question that is not answerable as formed.






Mike Halloran
Pembroke Pines, FL, USA

 

[BreadboardPerson]

In my application, safety under heavy load is important. In laymen term, how do the three motors ranked?

 

[SwinnyGG]

You have not provided enough information to answer your question.

What material the gears are made from is one of about 50 factors that should have an effect on your decision.

 

[MikeHalloran]

In my application, safety under heavy load is important.

Which is starting to smell like you are making a hoist or something similar, in which case there may be some regulatory considerations.

Where in the world are you, and what, exactly, do you intend to do with these (gear)motors?



Mike Halloran
Pembroke Pines, FL, USA