Injection Molding

“One Word: Plastics”. Injection molding is the process by which hot, liquefied plastic is injected into steel (or sometimes other materials) cavities called moulds, under high-pressure. There is a real art to injection molding that includes proper design of the parts themselves, the moulds that form the parts and the various parameters that can be tweaked during the injection process itself. For now, suffice to say that all of the plastic components of your product are made – one at a time – using this process. In the photo at the very top of this post, this would include the white housing components, black belt clip and battery door, translucent LCD cover, rubber buttons and even that tiny, little white spec which is the “Set” button from the rear of the unit. One or two workers typically operate the station. A first worker runs the injection molder, removing each newly molded part by hand. A second worker removes flash – excess unwanted plastic – from the finished part using a knife. The final parts are carefully stacked in bins for transport to the assembly area mentioned above or, if injection is an outside process, for shipment to the main factory.

Tool & Die Making

Closely related to injection molding is the tool shop. Again, not every factory has injection molding in-house and even those that do may outsource the creation of the steel tooling to an outside specialty house. Creation of the steel tooling is one of the longest stages of the product design process – typically taking 6-8 weeks from beginning to end. Steel blanks are machined using CNC (Computer Numerical Control) Machines or by another process called ECM (Electrochemical Machining). In another post perhaps I’ll talk a little about the design of plastic parts which, in addition to serving their intended purpose in your product, need to be designed in such a way that they can be easily injected. Smart design of your plastics will allow you to avoid features that are difficult to mold, resulting in mechanical apertures called “actions” which make your tools more complex and more expensive. A basic understanding of plastic part design is important for this reason. As someone new to this world, you may have a state-side company design a basic CAD database and they may not do it well. The Asian factories you ask to quote your part will typically not question your design and you may get back extremely expensive quotes (thereby deflating your entrepreneurial spirit) for a part which, if designed slightly differently may have resulted in tooling charges a fraction of the cost. Even slight knowledge – “talking points” type of knowledge – of every aspect of the design of your specific type of item will go a very long way. This is akin to the consumer who gets ripped off by the local garage because they don’t understand that cars no longer have carburetors, distributors or batteries that need refilling. A basic knowledge of your car may save you a lot of money at the repair shop.

Painting & Deco
Painting of plastic parts that are not molded in color is typically done using masking and spray booths. One of the nice touches that we added to the Klip! timer is a rubberized paint on the rear housing, belt clip and battery door. This rubberized paint makes the product nicer to hold and gives it a higher-quality appeal. It is worth noting, that this rubberized paint is not without a cost. I believe the upcharge is something like 10-12 cents, which by the 4x rule, is approximately forty cents at retail, but we felt it was important. Determining your target retail price point and understanding whether or not you can make your item for a cost that will allow for that retail price is extremely critical and should predate any discussion with designers or factories. Alas, this subject is again a topic for another day.

“Deco” refers to lettering or other graphics which are applied to the product using processes known as pad-printing or silk-screening, to name two. I won’t get into the details of these processes but typically the results from silk-screening are better but the shape and size of your part may limit your ability to use this process in some cases. Pad printing is a more flexible alternative in that case.

Quality Control (QC)
Quality Control is such an important topic that I can not possibly address it in a paragraph or two. Suffice to say that QC is not a single “station” – it is a thought process, a way of factory life and something that takes place (or should take place) throughout the plant. There’s inbound QC, in-line QC, outbound QC and third-party QC. For today, your take away should be that if you visit a potential manufacturing partner you are going to want to grill them on what their QC process is and any good factory will want to show-off their attention to this aspect of the manufacturing process.