Innovation from OGM eliminates gas traps in injection mould tools

A new innovation from OGM, a leading plastic injection moulding company, will help to eliminate the problems caused by gas traps in injection mould tools.

Gas traps are a common problem in injection moulding, and can lead to scorching, pinholes, and poor finished part quality.

They are caused by gas pockets forming as the melt fronts of the molten plastic, which is injected under pressure into injection mould tool cavities, come together before the gas has escaped naturally through the split lines of the tool, which traps the gas.

Best practice in part design, tool design, and the use of mould flow simulation can alleviate the risks of gas traps, but they can still occur.

The proactive solution, where the exact location of a trap is unknown, is typically to fabricate the tool with inserts made from specialised porous materials in the critical areas, or retrospectively to a vent pins to the exact site of the problem.

However, neither of these options are ideal, are principally on the grounds of cost and time.

The solution developed by OGM uses the company’s latest hybrid metal additive manufacturing technology.

This has been adopted to produce a wide range of mould tool inserts quickly and at a competitive cost.

Using newly developed technologies, OGM is able to build inserts layer by layer that incorporate large number of micro-pores, each just a few microns in diameter, through which gas can escape, without adversely affecting the quality of the finished part.

The inserts are 3D laser sintered in steel or other metals, to match the exact requirements of each injection mould tool.

The dimensions and characteristics of the gas escape channels are optimised to reduce cycle times and boost productivity, while maintaining high levels of part quality, even for extremely complex designs.

Marcel Gowers, Additive Manufacturing Application Engineering Manager at OGM, said: “The process we’ve developed exploits the potential of 3D laser sintering, to create precise and carefully controlled vent channels through carefully selected areas of the injection mould tool.”

“OGM’s porous inserts can be manufactured into any 3D shape, both quickly and efficiently, enabling us to reduce lead times to a minimum, and just as importantly, we can help customer eliminate the problems caused by gas traps while maintaining moulded part quality and productivity.”