Mechanical Efficiency

[hvaldez]

hi everyone;

My company just started an initiative to improve the Efficiency and Performance of our processes. I am performing the analysis of the human factors and equipment factors and how they are related each other in the process. One of the aspects I need to consider is the Mechanical Efficiency of our equipment and tools. Is anyone familiar with this kind of analysis?

 

[plasgears]

Mechanical efficiency can be boosted a number of ways:
- plastic instead of metal gears in drives if allowable;
- reduced viscosity lubes in drives;
- spur gears instead of worm;
- examine kinematics for opportunities for improvement. A poorly designed linkage system can increase loads considerably.

 

[EnglishMuffin]

plasgears : I am interested in your contention that plastic gears are more efficient than metal ones. Is this because they can be run with minimal lubrication and hence low churning losses, or are there deeper reasons ?

 

[196402]

The idea of line balancing can be of help. Find the right software at

http://www.osmec.com/SmartSoft/SOFTWARE....

 

[plasgears]

Muffin,
We have found that when a plastic gear (acetal, nylon, e.g.) is substituted for metallic, the efficiency goes up, and the prime mover needs to be downgraded to maintain reasonable stall torque. There is a smoother contour in plastic gears, and they have self-lubricity. In addition, contact ratios tend to improve with flexible plastics. This is particularly important in automotive worm drives.

 

[EnglishMuffin]

Plasgears : A smoother contour? Do you mean a better surface finish ? Normally one operates metal spur or helical gears with an oil film thickness in excess of the peak to valley surface roughness height and it's possible to get, say, 98% efficiency per mesh. So improving on that wouldn't make a great deal of difference anyway. Of course, if you are talking worms, it's a little different story.

 

[Barry1961]

Worm gears are the most inefficient gear set I know of I would avoid them like the plague. Not only for the increased electric bill but the high maintenance. There are several mfgs making right angle gearboxes with hypoid or helical gears that are efficient, durable and inexpensive.

As far as plastic goes I have found that most gearboxes that have a plastic gear are gear limited. This means you end up with a bigger motor for less torque output and a good chance to strip the gear when a jam occurs. Plastic gears are great in the right application just be carefull.

When sizing drives try to find the actual torque and speed you need instead of just going by horsepower inupt. Some worms gears are only 40% efficient so you may be able to use half the motor. Also some gearboxes with plastic gears are limited to 20% of possible torque so you may be able to use a much smaller motor.

Barry

 

[plasgears]

Muffin,
Plastic gears as molded exhibit no tool marks in general. This contributes to higher efficiency. The factor of self lubricity is important. Most of the time that gears are in engagement they are sliding one upon the other. A synergistic combination is acetal against nylon, according to DuPont.