FEATURE MICRO MOULDING
SO YOU WANT TO MAKE A SMALL MOULDED PART?
Aaron Johnson, Vice President of Marketing & Customer Strategy at Accumold considers the challenges of micro moulding and where this sits within the realms of design for manufacturability
certainly by the overall part size but it also encompasses parts with micro features or micro tolerances. It is possible for “larger” moulded parts to fall within the true micro moulding realm if there are certain, feature, quality or complexity requirements that are on the more extreme side. A good rule of thumb to go by is, if the part can be manufactured by most general moulders in the company’s supply database there’s a good chance it’s not really a micro moulded part. Just because it’s small doesn’t mean it is micro moulded. Why does this matter? The answer lies
P
erhaps like no other, the field of microelectronics exemplifies the drive
towards miniaturisation. The extent to which products containing electronic components has risen at staggering rates and the pressure is not showing signs of slowing. At the same time the demand has shifted from a general, “make this smaller” request, to a, “make all the components inside smaller too.” This natural progression of wanting to have more complexity inside an already tight form-factor has put more pressure on design engineers being asked to achieve the impossible. One of the key enabling technologies in the miniaturisation phenomenon is micro- injection moulding. Electronics and plastics go hand-in-hand these days and plastic is the perfect complement to the size reduction challenge. The micro moulding of tiny connectors, housings, optics or
20 SUMMER 2015 | MICROMATTERS
whatever the mind dreams up has brought component design to a whole new level of complexity. A wise mechanical engineer once said, “Everything I draw is the size of my monitor.” Jesting aside, new ideals of micro and complex are being imagined and realised everyday with micro moulding. The challenge with micro moulding
begins when the project moves from the digital to the physical stage. When the reality of the designed features are measured in a few millimeters or even microns the actual manufacture of these parts can seem near ridiculous. So what does one do?
MICRO MOULDING DEFINED First off, a general definition of micro moulding is in order. In simple terms it’s just like general injection moulding only smaller. Micro moulding can be defined
Figure 1:
The micro moulding of tiny connectors, housings and optics amongst other things has brought component design to a whole new level of complexity
where general moulding ends and micro moulding begins. People ask all the time if there are guidelines to go by when designing for micro moulding. The answer is, “yes,” and “no.” There is no cut and dry rule that works for all situations. The zone between general moulding and micro moulding is fuzzier than it is clear. Geometry, material, quality, features, tolerances and/or annual unit demand all can have a profound effect on the success of any given project. What can work for one project may fail miserably for another. Again, what to do?
DESIGN FOR MANUFACTURABILITY Probably the single most important part of any micro moulding project happens long before steel is cut for the mould. In virtually every case, a micro moulded project starts with a Design for Manufacturability (DFM) conversation; an actual human-to-human conversation. It’s not an uncommon practice for a designer to pick a moulder, upload a 3D file to the web, and have it spit back a quote in moments. This is just not so with true micro moulding. The relationship between the geometry, the material and quality requirements are too complex for a simple response. In fact, up until recently, most flow analysis tools suggested micro mould parts were not even mouldable. At the same time some
/ MICROMATTERS
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