Injection moulded plastics engineering features

Overmoulding

I have designed several products with overmoulding of plastics and synthetic rubbers in different combinations. I have expertise in the compatibility and mouldability of these materials when combined to make a product part.

Snap fits

I am very experienced in the design of these useful features, integral in mouldings, taking advantage of the resiliency of most plastics, like Nylon, Acetal, Polycarbonate, ABS, Polypropylene and other plastics. I am able to carry out Finite Element Analysis to analyse their performance

Clamp for toy Prototype and injection moulded part with integral snap fit	Urine sample collection funnel with integral snap fits that engage on container below	Engaged with container The snap fits allow for different container types
Plastic tile with integral snap fits that engage with receptacles below	Tile underside Receptacles that engage with snap fits	Medical product which is entirely assembled with accurate snap fits
Baby teether with integral snap fits having a moulded-in living hinge	Medical product above 3D printed prototypes to test mechanical features.

Moulded-in elements

I am able to design mouldings with moulded-in elements such as threaded inserts, magnets, anchors and other mechanical parts

Silicone pouch with moulded-in magnets	Strap with magnets to attach the pouch

Design to prevent sink marks

Apart from knowing the necessary design features, to prevent sink marks, I carry out computer analysis to observe where there is a risk of sink marks and distortions which can appear after making costly moulds.

Sink marks analysis	Warp analysis

Demoulding provisions

These consist of the necessary design features to be able to remove the part from the mould, automatically, after it has cooled down.

Analysis to seek so called 'undercuts' that can catch the part in the mould, preventing it from being ejected	Analysis to check the walls angles (draft angles) to allow the part to come off the mould

Integral hinges

Materials like Polypropylene and Polythene allow the creation hinges, integral in the part, which can be used to provide useful features like lids, snap fits and other elements.

Snap components with integral hinges	They are folded with the hinge to snap on a part made of cloth in this instance

Spring design

Using the mechanical strength and resiliency of plastics like Acetal, Polycarbonate and Nylon, I am able to design integral springs that will last many cycles. I carry out Finite Element Analysis to design them.

Components with integral springs	FEA analysis to determine weak areas With this analysis the design of the part can be adjusted to reinforce the part against breakage.

Moulded threads

I know the necessary design detailing to be able to mould threads whilst it is possible to remove the part from the mould.

Moulded threads, such as on bottles	Fine CAD detailing of threads This can include sealing against escape of liquids.

Design to integrate features avoiding side cores

Even though side cores are useful, and often used, in injection moulding it is more economical to design features that avoid them and the moulding of them is done with the two halves of the mould.

Product using linked plastic mouldings These are the green parts, designed to be made with the two halves of the mould, only, whilst having features that would require side cores if no creative thinking is used in their design.	Design of features to avoid side cores

Mechanical components

Knowing the use of engineering plastics, which can carry out the functions of metals, is very useful when the product will be made in mass production as it avoids the costly processing of metals, such as CNC machining, castings and the like. Moulding engineering plastics also helps design complex parts which cannot be made in materials and processes such as sand castings, sheet metal, wood and others.

Dispensing device Almost all metal part are replaced with engineering plastics	Holder of 3D glasses to prevent theft Strong mechanical parts to be made in injection moulded engineering plastics.

Injection moulded plastics engineering features

Overmoulding

Snap fits

Clamp for toy

Prototype and injection moulded part with integral snap fit

Urine sample collection funnel

with integral snap fits that engage on container below

Engaged with container

The snap fits allow for different container types

Plastic tile

with integral snap fits that engage with receptacles below

Tile underside

Receptacles that engage with snap fits

Medical product

which is entirely assembled with accurate snap fits

Baby teether

with integral snap fits having a moulded-in living hinge

Medical product above

3D printed prototypes to test mechanical features.

Moulded-in elements

Silicone pouch with moulded-in magnets

Strap with magnets to attach the pouch

Design to prevent sink marks

Sink marks analysis

Warp analysis

Demoulding provisions

Analysis to seek so called 'undercuts'

that can catch the part in the mould, preventing it from being ejected

Analysis to check the walls angles

(draft angles) to allow the part to come off the mould

Integral hinges

Snap components with integral hinges

They are folded with the hinge

to snap on a part made of cloth in this instance

Spring design

Components with integral springs

FEA analysis to determine weak areas

With this analysis the design of the part can be adjusted to reinforce the part against breakage.

Moulded threads

Moulded threads, such as on bottles

Fine CAD detailing of threads

This can include sealing against escape of liquids.

Design to integrate features avoiding side cores

Product using linked plastic mouldings

These are the green parts, designed to be made with the two halves of the mould, only, whilst having features that would require side cores if no creative thinking is used in their design.

Design of features to avoid side cores

Mechanical components

Dispensing device

Almost all metal part are replaced with engineering plastics

Holder of 3D glasses to prevent theft

Strong mechanical parts to be made in injection moulded engineering plastics.