MOULDING
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Addressing moulding issues early on during the product design phase can save a lot of time and money down the line.
(Photo courtesy DA/PRO RUBBER) |
Choose a Long-Term Partnership
The moulding process is most effective when you and the moulding engineer work closely from the beginning of the design process all the way to first article. “This way moulding concerns can be addressed at the design phase and not after the design is approved, providing a much more efficient process,” says Robert Ballard, Engineering Manager, Da/Pro Rubber Inc. (Valencia, CA, USA).
Early partnering provides an opportunity to consider how your project will be managed regarding both time and budget targets, adds Martin Day, Sales and Marketing Director, Carclo Technical Plastics Ltd (Mitcham, UK).
Apply Design for Manufacture Principles
When designing a new part, it pays to consider design for manufacture as soon as possible to avoid expensive mistakes, says Day.
To ensure manufacturability, first articles off a new tool should always be delivered to verify acceptability. “It is often better to do a functional test on the part than to rely on measurements,” Ballard adds. This way, modifications can be made to a part and/or process in a timely fashion.
Think Beyond the Prototype
Consider manufacturing scale-up from the start of your project. “Your moulding partner will suggest the most effective and cost-efficient methodology for manufacturing your part,” says Ballard. “Some factors in determining the method of moulding (liquid injection, compression or transfer moulding, for example) are the quantity of production parts expected, the design of the part, and the material used,” he adds. “Make sure your moulding partner is aware of any special measurements.”
Edi Celidoni from Lucomed SpA (Carpi, Italy) notes that quality means accuracy from raw materials selection to enforcement of reliable quality control systems in every production and distribution step, not just in the prototyping stage. Look at the whole picture, she stresses. “Investments made by your supplier in R&D must help in the long term.”
Be Detail Oriented, But Stay Flexible
Some of the things a designer should consider include detailed dimensions, tolerance of the dimensions of the product to be moulded relative to the mould itself, flash considerations and parting lines. “Tolerancing can significantly affect the ability of a final part to meet the print, or even whether the part can be moulded,” Ballard says. “Allowable tolerances, including Cpk requirements, are a must.”
All necessary information must be included in your drawings in order to determine the mouldability of the part. Three-D models are also helpful. The moulding engineer should recommend design changes that make the component more mouldable.
It is important to think about the total life cost for the product. Discussing all usage issues with the moulding partner will avoid over- or under-specifying materials, which can have a great impact on cost. “If a material is approved before discussing it with the moulder, you run the risk of eliminating more efficient methods,” Day says.
Put It in Writing
As you progress through your project, keep every detail, every change, every modification in writing. All suppliers agree that nothing can ruin product development more than not being on the same page when parts are ordered.
