Many people come to us just getting started with their projects. It’s very easy to be overwhelmed by the choices of plastic manufacturing processes available. We like to help, so we’ve made this infographic to try and distill this information down a little bit. Remember, you’ll still need to make decisions about process after looking at this – but it should steer you in the right direction.

Please note that while every effort has been made to ensure the accuracy of this information, some of these methods fall outside our specialisation area. We welcome feedback and any corrections via the email address at the top of the page. 

Plastic Manufacturing Process Infographic blow compression injection moulding 3d printing cnc machining casting thermoforming

 

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Which Plastic Manufacturing Process is the right one for me?

How you get your plastic part made depends on (mainly) 5 factors:

  • Form
    • What shape are your widgets? This will be determined by function and limited by the restrictions of the manufacturing processes available.
  • Budget
    • Part cost + tooling cost. Some methods have expensive set up costs. Some are quite cheap but there’s usually a trade off. Most high volume manufacturing processes are expensive to tool, but offer cheap parts – the opposite is also true: low volume processes are cheap to setup but parts are expensive.
  • Volume (closely connected to budget)
    • Total run? Annual quantity? You should be able to calculate the best manufacturing method by factoring in part price and annual volume. Many manufacturing methods offer multi-impression tooling which means you can make multiple parts per cycle. Cooling is more expensive but part cost is considerably reduced.
  • Time
    • Tooling takes time, manufacturing takes time. More expensive tooling usually means longer setup time. Injection moulding tools can take 10-16 weeks to manufacture. Multi impression tools can reduce production time as multiple parts are made every cycle.
  • Material
    • Material choice is determined mostly by form, function and cost – it’ll also depend on what manufacturing technique you choose e.g. if you want a bakelite product, you’ll not be able to injection mould it.

Low Volume Manufacturing Processes.

Fabrication

Fabrication is a catch all term for any type of small scale manufacturing for prototyping that doesn’t involve digital technology.

  • Production time: ****
  • Setup cost: *
  • Part cost: ****

Materials:

  • Acetate
  • Polystyrene
  • Acrylic
  • Bakelite

Form

Parts are made from glueing, turning, carving, welding and many other methods.

CNC Machining

Take a block of material, a 3D model, plug it into the computer then leave the machine to do the work. A combination of drilling, milling, grinding and other methods – all computer controlled.

  • Production time: ****
  • Setup cost: *
  • Part cost: ****

Materials:

  • Wood
  • Plastic
  • Metal

Form

CNC machines are a form of subtractive manufacturing so you’re always cutting away from a block of something. Complex internal structures are difficult to create unless they’re accessible from the outside of the component.

3D Printing

Take a 3D model, plug it into a computer, then leave the machine to do the work.

  • Production time: ****
  • Setup cost: *
  • Part cost: ****

Materials:

  • Plastics: PLA, ABS, PVA
  • Powders: Polyamide, Alumide
  • Metals
  • Resins
  • Ceramics

Form:

3D Printing machines are cheaper than CNC. Remember, you’re printing from the bottom up, so to print structures with overhangs will need extra support structures. Complex internal structures are possible with 3D printing and high spec metal 3D printing can be used for creating light but incredibly strong parts.

Medium Volume Manufacturing Processes.

Casting

Molten plastic or metal is poured into a mould, then solidifies. The mould is cheap and can be made from plastic but production time is quite long.

  • Production time: **
  • Setup cost: *
  • Part cost: ***

Materials

  • Acrylic
  • Bakelite
  • Polyurethane

Form

Thick parts can be moulded with casting. Curing takes time but thick wall sections are achievable.

Thermoforming

Sheets of plastic are warmed and sucked onto a mould. Neither pressure or high temps are required so moulds can be made from cheap materials.

  • Production time: **
  • Setup cost: **
  • Part cost: **

Materials

  • Most sheet plastics

Form

Shape determined by single-sided mould. Cup form possible, but quite limited in terms of shape.

 

Rotational Moulding

Molten plastic is poured inside a large mould which is then rotated until the plastic covers the inside of the mould.

  • Production time: ***
  • Setup cost: **
  • Part cost: **

Materials

  • Polyethylene
  • Polypropylene
  • Polyamide

Form

Shape of rotational moulded parts restricted to medium to large hollow forms with uniform wall sections e.g. traffic cone or water tank.

 

Compression Moulding

Material is added to a two-part mould and heat and pressure is applied.

  • Production time: ***
  • Setup cost: ***
  • Part cost: ***

Materials

  • Melamin
  • Bakelite

Form

2-part mould but quite limited. Cup shapes possible but no holes in the side of cups possible.

 

High Volume Manufacturing Processes.

Extrusion Moulding

Plastic granules are melted and pushed through a die creating a continuous length of plastic with the desired form. Think “sausage mincer” with heat.

  • Production time: *
  • Setup cost: **
  • Part cost: *

Materials

  • Many plastics including:
  • PVC
  • HDPE
  • Polystyrene
  • Synthetic Fibres

Form

Anything that can be pushed through a die. Sheeting, tubing, bags, guttering etc.

 

Blow Moulding

Hot air is blown through a pre- fabricated tube (often made by injection moulding) pushing the semi-molten plastic outwards against the form of the mould.

  • Production time: *
  • Setup cost: ****
  • Part cost: *

Materials

  • HDPE
  • PET

Form

Any article with a mouth smaller than body. Bottles, containers etc.

 

Injection Moulding

Plastic granules are melted and injected into a 2-part mould, cooled into a solid and ejected.

  • Production time: *
  • Setup cost: ****
  • Part cost: *

Materials

  • All thermoplastics.

Form

Highly precise technique capable of very sophisticated forms and shapes. No hollow forms and no thick wall sections.

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