10 Other Design Guidelines For Injection Molding

When designing for injection molding, there are even more guidelines to consider. The easier it is for toolmakers to create your mold, the faster your turnaround time, which will increase the speed with which your product will be available to consumers. Here are 10 other design guidelines to follow when designing for manufacturing:

  1. Consult your manufacturer about solid mounting characteristics or device location. Experience counts in this area and you want to be a tough man. Threaded components can often be replaced by simple male-female connectors. Simplicity, like everything else, is the key here.
  2. Avoid small holes. Small holes may be too complex to mold well. This will also increase the risk of breakage of the tool. Both will increase your costs.
  • If you make a hole in your injection mold, the through-holes are preferable. This will allow the mold to separate more efficiently and ensure a uniform hole diameter.
  • If there is a difference in angle or surface consistency. It will depend on the material used. Whether or not, the variance is not perceptible to the human eye. However, if your design requires an exact surface or angle, specify a material that will hold its shape, such as low carbon hot rolled steel.
  • Flatness must be applied both per unit and with a reasonable overall shape tolerance. This will avoid sudden surface variations or the characters in a relatively small area.
Injection mold
Injection mold
  • Dimensional tolerance. Shift the machining tool to allow dimensional tolerance. The “milling compensation” takes into account the size of the tool itself in the tooling of the mold.
  • Consider stack tolerance for related parts. When creating connection parts, consider the separate tolerances on the male and female connectors. If the tolerances are considered unrelated to one of them, the parts may not mate, resulting in costly changes.
  • When a design requires a particular orientation, provide a design element to make it clear. If you are unable to design your room with clear instructions and incorporated into its design, you must consider a new design.
  • Use uniform screw sizes if possible. Think of the end-user in your design process. The use of uniform screw sizes and “standard” components will make your design much more accessible to more people.
  1. Keep your coins. Each additional component of your design multiplies the risk of error. In addition to keeping the design or your piece simple, it’s important to keep the design as a whole as simple as possible. The solution is to create a design that optimizes the injection molding process.

Plastic injection molding is an effective tool for creating consistent and well-designed parts for your design. However, you must make it work for you. The easier you do for toolmakers, the sooner you will see a return of your design.

The most popular plastic molding company

Plastic molding is a process that producers thermosetting and thermoplastic plastic materials. The process involves sending the material a warm barrel where it is melted down for mixing. After being melted and combined, the material is sent into a mold where it is left to chill and solidify into the same shape as the mold. Other materials, such as steel and aluminum, are generally molded after plastic molds as well. Some of the plastics contain polycarbonate, nylon, Teflon, acrylic, acetal, PVC, polystyrene, PVC and more. Since these are the most general forms of plastics, they make it simple for any person to acquire the material required for a plastic injection machine.

Plastic molding company and process

Plastic molding is made by warming polymer resin under high pressure and temperatures (generally between 200 C to 400 C depending on the material features). Once in a soft malleable form, the hard polymer is located under rollers to bring about a fixed particular shape before being cut to the right shape. What makes plastic molding such as a perfect system is that it comes to a low cost and can produce big quantities of material. As described earlier, the plastic molding process is amazingly versatile and can provide a big range of different molded parts and include a perfect finish to the parts as well.

Plastic molding company
Plastic molding company

The general idea in plastic molding is adding molten liquid plastic into a ready shaped mold, for example, the mold of a bottle. It will then be permitted to chill, then the mold will be removed to show the plastic bottle. Compression molding generally uses vertical presses instead of the horizontal presses used for blow and injection molding. The parts formed as then air-chilled. If you are planning to go into a plastic molding business, you should primary know the different processes. Pick from an injection molding process that fits your budget, your resources, and your expertise.

Two of the general needs of understanding injection molding manufacturer is perfect chemical expertise and mechanical proficiency. While the machines that mold and shape the stuff are complex in technicality and need very professional workers to operate, the polymer resin itself must be well understood to use it rightly. Even the keyboard and the mouse that you use are made via plastic injection. Even the plastic parts of the chair that you are sitting on are made this way. Today’s varied needs and design abilities have made it easy to have custom made plastic items as specified by an individual.

Case Study

We have been with ST plastics since Royston and Bob took the reins some 3-4 years ago. ST have designed injection moulding tools to our specifications for over 20 product lines and supply us with a continuous stream of plastics which are used in our product and exported globally. Staying on shore and particularly with ST has proved to be a very smart management and fiscal move. Their co-operation, liaison, reliability, communication and willingness to accommodate change far outweigh any perceived savings one might achieve using resources off shore. Not to say ST are not competitive, they are, but the quality and reliability from the ST team are second to none.

plastic moulding

managing director


I have had dealings with ST for the past 5 or so years, and the service and response to any given problem is truly fabulous. I design machinery for a living, and plastics and associated materials form a very important part of the design process. Most important to the process is, I find, the need to obtain advice and assurances that a certain design is possible, and this is often required very early in the design process. I have found that ST Plastics are very capable of this, and it saves many days , even weeks in design work.

Their early evaluation of the design and how it might be cast in what product has been close to faultless. This is, in my opinion, what sets them apart from the typical toolmaker who often requires detailed drawings before you can get past the front door.

Their tool making expertise has been very good, allowing and preempting the shrinkage rates and distortion that will occur with many moulding procedures.

Very Very impressed with your entire business and service. Regards Paul Willett, Managing Director,

I am writing to endorse and highlight ST plastics .Bob & Royston have provided us with fantastic service right from the first contact , besides being professional and friendly they have made themselves available to us , which can be very reassuring .

Our line of work is in commercial construction, so time lines and installation schedules are tight & limited. Taking this into account Bob &Royston not only took the projects on but created working drawings & helped with design issues together with managing to supply us the finished product before the due date, enabling us latitude to complete our manufacture. In closing I can do nothing but recommend ST plastics to anyone that is in the market for their services. Dealing with them is easy & you can be confident of the service & outcome you require which makes them a perfect choice to help grow & improve product lines & productivity.

Yours thankfully



I have had a long business relationship with ST Plastics and have always been happy with their service and expertise. Since taking over the business a few years ago, Royston and Bob have worked hard to take the company to another level. Their commitment to service, quality and customer satisfaction is honest and real. If you have need of injection mouldings look no further.


Managing Director

As manufacturers of the Odalog Gas Logger and Gas Detector range, Thermofisher Scientific, like our customers, demand only the highest quality and accuracy from our high-end gas instruments. Our instruments meet the needs of their industry, whether in a rugged underground mining environment or in the corrosive wastewater monitoring, so we need to be sure that the plastic parts that house our compact electronics are up to the job. At ST, our extremely high standards are completely understood and catered for with high quality, precision and repeatability of our ‘unconventional’ plastic moulding – even in small batches. With the experience, technical advice and superior customer service ST offer, we wouldn’t consider going anywhere else.

plastic molding

Design Engineer (Mechanical Engineer / Industrial Designer)

I have to compliment you, and all others of your company – and I don’t hand out compliments freely. As you might expect, in looking for a company to do this work for us, I contacted multiple Australian companies who advertise on the net claiming a high tech capability for tooling and production of prototype runs. All other replies I received demonstrated incompetence (at least in communication) or just plain disinterest.

You replied with intelligent communication and followed up with a phone call. Subsequently you have been most courteous in all contacts with me, and have demonstrated a high level of competence in the quality of the samples received today. Thus, in my view, ST sets a benchmark to which others should aspire. May your company enjoy well deserved success.

Geoffrey Wickham A.O.