Polypropylene (PP) Plastic Machining

Your guide to Polypropylene Plastic Machining

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Known as 'the steel of the plastic industry’

Commonly used for mechanical components in corrosive environments

More readily available alternative to ABS

Polypropylene is a thermoplastic that is available as a Copolymer and Homopolymer. It is commonly used for mechanical components in corrosive environments.

It can be challenging to machine because of its low annealing temperature. It therefore requires a high level of skill from a trusted CNC machining partner.

This guide will take you through the main attributes, common applications, notes for designers and suitable finishing and treatments, as well as UK stock sizes and property tables. Don't forget to bookmark the page so you can refer back later.

If you are interested in Polypropylene machined parts, please scroll to the bottom of the page for more information about our service and to request a quote.

Polypropylene Guide: Properties, Applications and Design Considerations

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What is Polypropylene plastic?
 
Polypropylene (PP) also known as polypropene is a hydrocarbon polymer and is one of the most commonly produced plastics in the world.

It is sometimes referred to as the ‘steel of the plastic industry’ due to its adaptability.

PP is a thermoplastic that is available as a Copolymer and Homopolymer. It is commonly used for mechanical components in corrosive environments.

Polypropylene has gained a reputation for being tricky to machine due to its low annealing temperature. It therefore requires a high level of skill.

As well as a sharp cutting edge and slow feed rates, we use plenty of coolant to aid lubrication, remove swarf and help keep the PP below its melting point.

Penta Precision has decades of polypropylene machining experience so you are in safe hands.

You may also see Polypropylene referred to as:

  • PP
  • TECAFINE® PP
  • TECAPRO® - medical grade 
  • PPC / Polypropylene C (Copolymer)
  • PPH / Polypropylene H (Homopolymer)
  • Proteus®
  • Orthoform®
  • SIMOLIFE
  • Polystone®
  • ProComp
 

Industry Examples: Medical | Pharmaceutical | Chemical | Food processing | Packaging | Automotive

 

Typical Components & Applications: Valves | Galvanizing apparatus | Filter components | Bearings | Packaging | Housings | Flanges | Living hinges | Wear pads | Machine cases | Seals | Pump components | Gears | Vacuum systems | Chemical processing & storage applications | Orthotic & prosthetic devices | Plenums & manifolds | Household appliances

 
Main Attributes:
  • Good to excellent chemical resistance
  • Semi rigid
  • Good fatigue resistance
  • Integral hinge property
  • Good heat resistance
  • High flammability
  • Excellent electrical resistance
  • Low density
  • Lightweight
  • High purity
  • Low moisture absorption
  • High thermal expansion
  • Food compliant
  • Excellent weldability
  • Stain resistant
  • Low thermal and mechanical properties in comparison to engineering plastics
  • Poor UV resistance
  • More readily available alternative to ABS
  • Low cost
  • Recyclable

Note For Designers:

Polyethylene is available as a Homopolymer (PPH) and Copolymer (PPC). Material selection may depend on application and desired properties although the attributes are very similar and they are largely interchangable materials. Here is a brief overview of each.

Homopolymer Polypropylene

PPH is the more widely used general-purpose grade of Polypropylene. It has improved chemical resistance and stiffness and also has a higher working temperature than the PPC variation (0-100°C). It is slightly more expensive than PPC although still relatively inexpensive.

Copolymer Polypropylene

Although PPC has a relatively lower chemical resistance than PPH, it is still considered to be very good. Its operating temperature range is not as high (up to 80°C) but it has improved impact strength at lower temperatures (down to -20°C).

It also has lower susceptibility to stress cracking. Whilst both are suitable for use with food, the copolymer is more commonly selected for food-related applications. PPC is more transparent than PPH and generally used where more flexibility is required.

PPC can be further divided into random and block copolymers, produced by the polymerizing of propene and ethane.

Random Copolymers

Random copolymers features up to 6% Ethene which is randomly dispersed. They are flexible and optically clear.

Block Copolymers

Block copolymers feature between 5 and 15% ethane and the co-monomer units are arranged in a regular pattern, making it tougher and less brittle.


Finishing & Treatments:

Polypropylene has poor bonding properties and is therefore difficult to paint so we do not advise it.

See our Finishing Processes page for further information on services that we can facilitate.

Can we meet your polypropylene machining needs? Contact us now
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Further Reading & Resources

British Plastics Federation

CNC Machining Changing Supplier Guide

Polypropylene Plastic Machined Parts

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Penta Precision provides the following plastic polypropylene (PP) machining services: 
  • CNC milling
  • CNC turning
  • Prototypes and batch runs
  • Insert installation
  • Part marking
  • Manual milling
  • Manual turning
  • Machining design advice
  • Design for manufacture service

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