Plastic Injection Moulding

Our plastic injection moulding process produces custom - rapid prototypes and end-use production parts in 15 days or less. We use aluminium moulds that offer cost-efficient tooling and accelerated manufacturing cycles, and stock more than 100 different thermoplastic resins.

Plastic Injection Moulding Design Guidelines will help you understand capabilities and limitations.

 

Why Choose Plastic Injection Moulding For Your Project?

Protolabs utilise a rapid injection moulding a technology-driven process that leverages manufacturing automation. CAD models are sent directly to the production floor where mould milling begins, but in most cases, moulds are fabricated from aluminium, not steel. This allows for faster and most cost-effective tooling when compared to traditional steel moulds.. We offer a number of additional moulding and tooling services to support your project.

 

What is Injection Moulding?

Plastic injection moulding is the process of melting plastic pellets (thermosetting/ thermoplastic polymers) that once malleable enough, are injected at pressure into a mould cavity, which fills and solidifies to produce the final product.

 

How Does Plastic Injection Moulding Work?

The thermoplastic injection molding process at Protolabs is a standard process involving an aluminium mould with no heating or cooling lines running through it, which means cycle times are a bit longer. It allows our moulders to monitor fill pressure, cosmetic concerns, and the basic quality of the parts.

Resin pellets are loaded into a barrel where they will eventually be melted, compressed, and injected into the mould’s runner system. Hot resin is shot into the mould cavity through the gates and the part is moulded. Ejector pins facilitate removal of the part from the mould where it falls into a loading bin. When the run is complete, parts (or the initial sample run) are boxed and shipped shortly thereafter. Request your Free Design Cube which shows surface finishes and thick and thin finishes.

IM icon Logo
  • 25 to 10,000+
  • Shipped in 15 days or less
Common Applications
  • low-volume production
  • bridge tooling
  • pilot runs
  • functional prototyping


 

 

Watch: Injection Moulding

Rapid injection moulding works best for on-demand production, bridge tooling, pilot runs, and functional prototyping. Our affordable aluminium moulds and quick turnaround times help reduce design risks and limit overall production costs.



 

Three Types of Moulding 

Manufacturing has experienced radical change over the years, but one of the few constants has been the prevalence of injection moulding as the most common process within the sector. But what makes injection moulding so compelling to design engineers around the world?



Design Guidelines: Plastic Injection Moulding   

SIZE

480mm x 770mm

VOLUME

966,837 mm³ 

DEPTH

101mm from parting line with 3° of draft

Up to 202mm if the parting line can pass through the middle of the part
Projected Mould Area

112,903 mm²

 

Typically, Protolabs can maintain a machining tolerance of +/- 0.08mm with an included resin tolerance that can be greater than but no less than +/- 0.005mm/mm

If your part is outside of these listed tolerances, please contact us direct to discuss how we can help  applicationengineers@protolabs.co.uk

  • ABS
  • ABS/PC
  • Acetal
  • Acetal Copolymer
  • Acetal Homopolymer
  • ETPU
  • HDPE
  • LCP
  • LDPE
  • LLDPE
  • Nylon 6
  • Nylon 5/12
  • PBT
  • PC/PBT
  • PEEK
  • PEI
  • PET
  • PETG
  • PMMA
  • Polycarbonate
  • Polypropylene
  • PPA
  • PPE/PS
  • PS

VIEW MATERIALS >

FINISH DESCRIPTION
PM-F0 non-cosmetic, default

PM-F1

low-cosmetic, most toolmarks removed
SPI-C1 600 grit stone, 10-12 Ra
PM-T1 SPI-C1 + light bead blast
PM-T2 SPI-C1 + medium bead blast
SPI-B1 600 grit paper, 2-3 Ra
SPI-A2 grade #2 diamond buff, 1-2 Ra

Read our design tip on surface finishes 

VERTICAL FACES
0.5°
MOST SITUATIONS
MINIMUM FOR SHUT OFF
MINIMUM FOR LIGHT TEXTURE (PM-T1)
MINIMUM FOR LIGHT TEXTURE (PM-T2) 5°+

Read our design tip on Draft

Maximum Side Core Dimensions

WIDTH HEIGHT

PULL

< 213.84mm <60.38mm <73.66mm

Read our design tip on Undercuts

MATERIAL

RECOMMENDED WALL THICKNESS

ABS

1.143mm - 3.556mm

Acetal

0.762mm - 3.048mm

Acrylic 0.635mm - 12.7mm
Liquid Crystal Polymer 0.762mm - 3.048mm
Long-Fiber Reinforced Plastics 1.905m - 25.4mm
Nylon 0.762mm - 2.921mm
Polycarbonate 1.016mm - 3.81mm
Polyester 0.635mm - 3.175mm
Polyethylene 0.762mm - 5.08mm
Polyphenylene Sulfide 0.508mm - 4.572mm
Polypropylene 0.635mm - 3.81mm
Polystynene 0.889mm - 3.81mm
Polyurethane 2.032mm - 19.05mm

 * The table is adapted from manufacturingcenter.com.

Some part corners will have a radius rather than a sharp edge since we use an automated CNC milling process to make the mould for your parts. This typically does not require a change to your model, but resulting radii are identified before the mould is milled.

Read our design tip on Radii


How can I reduce mould costs?

1. Eliminate undercuts
2. Get rid of unnecessary features
3. Use a core cavity approach
4. Reduce cosmetic finishes and appearances
5. Design self-mating parts
6. Modify and reuse moulds
7. Pay attention to DFM analysis
8. Use a multi-cavity or family mould
9. Consider part size

 

Learn More about Reducing Mould Costs


What can Injection Moulding be used for?

Injection Moulding is used to make a variety of widely used products. If you look around your desk/ home you will find a multitude of injection moulded products, from bottle tops, remote control casing, console covers, syringes and most plastic made products.

To see an example of an injection moulded part worked on by Protolabs, please view our Hager case study here.

To show off some of the features our injection moulding service can offer, please click to register for your free design cube


 

Injection Moulding Quote: ProtoQuote with Design Analysis 

Product designers and engineers can upload a 3D CAD model online at any time to receive an interactive ProtoQuote® with free design for manufacturability (DFM) analysis and real-time pricing information within hours. The DFM analysis helps eliminate potential problems like sink, challenging undercuts or walls that are too thin or thick. Once a part design is ready and a quote approved, production begins almost immediately. Upload a part today for a ProtoQuote with design analysis.


Left shows a through hole. Right, is a pass-through core.

Our Latest Moulding Tip 

Needing to solve difficult tooling and design issues? Shut-offs are a design element that help engineers solve this. Read more about incorporating shut-offs into your mould design.


Further Information

For more information on injection moulding, please check out our White Papers and comprehensive library of design tips

Need support in choosing materials for your project? See our whitepaper on thermoplastics Materials Matter

For tips and advice on designing for injection moulding. See our whitepapers Designing for Mouldability: Fundamental Elements and Design for Mouldability: Complex Features

and for further support with cosmetic appearance of moulded parts. See our whitepaper on Cosmetics

We also have design compilations for injection moulding and the initial design process.


Resources

Press operator examines liquid silicone rubber part

Free mouldability analysis within hours

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