Plastic Gears

Advantages

Gear Design

Application

Today, though the plastic gear industry is still in the stage of infancy, but it can be said without any hitch that plastic gear manufacture is has made very important breakthroughs and gains in the gearing industry. Plastic gears are now being increasingly used in applications which were earlier thought not possible. Though the industry is thriving but there remains some level of skepticism. This skepticism is mainly due to the doubt, whether this plastic gears can match the metal gears in terms of matching high temperature or performing under very challenging conditions.

Helical Plastic Gear

Worm Plastic Gear

Bevel Plastic Gear

Pinion Plastic Gear

Other Plastic Gear

Spur Plastic Gear

Advantages of plastic gears
There are a number of reasons behind the popularity of plastic gears. The chief among them are the following:

• Economics
  The injection-molding process is very much cost effective process.
  
  
• Ease in manufacturing
  This is due to the non requirement of machining process as well the capability of fabricating with the help of inserts and compact designs.
  
  
• Special features
  It offers low density, lightness in weight and low inertia.
  
  
• Perfect shape
  Plastic Gears show an uniformity with regards to parts.
  
  
• Absorption capability
  Plastic gears show the ability for absorbing of shock and the resulting vibration. This is due to elastic compliance.
  
  
• Elimination of lubrication
  It has the perfect capability for operating with minimum or even no lubrication.
  
  

Plastic Gear Design
Plastic gears are essentially molded. Their shape is independent of the traditional hob designs. Plastic gear mold cavities are cut with the most sophisticated processes. Machineries used are wire EDM and other specialized machine tools. As only a single cavity is constructed in plastic gears for a particular gear shape, close attention is given to its design and development.

The profile of plastic gears is dependent on many factors. A typical profile of the plastic gear cavity looks like this.

The parameter influencing the design include the shape of the gear, material properties and shrinkage, the location and size of the gates etc.

Buyer's Guide To Plastic Gears
Listed here are a few of the questions that as an informed buyer you need to ask before venturing on to select the Plastic Gears.

• What function would the part perform?
• What is the lifetime that is expected of the part?
• Is there any need for agency approvals? (like UL, FDA, USDA etc.)
• What are the electrical characteristics needed and at what temperatures?
• What temperatures will the part be subjected to? And for what duration?
• Would the part be exposed to chemicals?
• Is resistance to moisture necessary?
• What is the procedure for assembling the parts? Can all the parts get combined into a single plastic part?
• Would it be a permanent assembling? Or one time only?
• Adhesives be used or not?
• Is there any requirement of fasteners?
• Would the part come under impact?
• What role would the surface appearance play? If it is vital then be careful of weld lines, gate vestige, parting line, ejector location etc.
• What color is needed for the part?
• How important is weathering or UV exposure?
• What are the tolerances that are required? Can there be a bit relaxation to make way for economy in molding?
• What would be the approximate weight of the part?
• Is wear resistance at all needed?
• Can the part be molded?
• Is there any undercut?
• Which are the sections too thick or thin?
• Is there any need for machining?
• Is there sterilization of the parts needed? If yes then types of methods (chemical, steam, radiation)?
• Is there any need for applying paints.

Application of Plastic Gears
There are many applications of Plastic Gears, they range from simple to very complex applications.

Quartz Clocks: A very popular application, Quartz clocks uses plastic gears that offer better operational ability than metallic gears.

Power transmission: Plastic gears are perfectly suited for the power transmission drives.

Other Applications:
Other popular applications for Plastic gears include:
- Printers, scanners and copy machines
- Paint mixing equipment
- Home appliances