The most common injection molding and mold making misconceptions


In manufacturing, it’s always good to follow best practices regardless of the process you intend to use – whether it’s 3D printing, CNC machining, or injection molding. These guidelines have been established for a good reason: they can help ensure the product’s quality and make the production process more efficient, but they can also sometimes overlap with what may be called “conventional wisdom”.

Often, this ends up being the reason why shops, professionals, or those unfamiliar with the depths of the process avoid carrying out specific processes or applications. However, some of these commonly accepted pieces of wisdom are no more than unfortunate misconceptions. As is the case with other plastic manufacturing processes, that also applies to injection molding and mold making.

Nonetheless, injection molding is the most efficient and cost-effective method for mass manufacturing plastic parts; it can produce millions of parts with exact tolerances in just a brief amount of time. To do this, you have to start by creating a mold, and that part of the process carries several misconceptions – just like injection molding itself. To that end, we’ll look at four of the most common misconceptions about injection molding and mold making.

You Can Mold Any Shape

Just as in the case of mechanical engineering, if you design a part, you have to make sure it’s manufacturable. And a commonly surprising fact is that not every shape is moldable. If you plan to mold a plastic part that is not easy to manipulate to a great degree, you will find yourself running into production problems in the process and overall quality issues.

Most designs whose geometry is not entirely moldable have to be modified to at least 90% of the original idea. Executing the part perfectly depends on the balance between the melt flow and the channels through which the heat is transferred. It follows, then, that if the plastic cannot freeze uniformly, you end up with a mold that is practically unusable and unfitting to its purpose.

Plastic Injection Molding Is Not Suitable for Prototyping

For several reasons, it’s a common misconception that plastic molding is not suitable for prototyping. More often than not, the assumption is that it is a resource-intensive technique that is not cost-effective or takes too long to finish. While other techniques are generally used more for prototyping, that can lead to a lack of resemblance with the final product.

Injection molding is, in fact, the most cost-effective solution for creating parts that closely resemble the end product. It can produce high-quality prototypes much faster than virtually any other option and deliver accurate reproduction of the product. Ultimately, this will allow for a better feel of the product and any additional changes without increasing the cost.

Injection Molding Is Only Used for Long Production Runs

The durability of the mold and its production cycles largely depends on your requirements. For instance, steel molds are specifically developed for long production runs, but molds made from other materials are widely used in prototyping and other types of short-run productions.

In fact, injection molding is a cost-effective solution for producing parts of any quantity – from several pieces of a prototype to large-scale, five or six-figure cycles. Even if you’re producing functional prototypes in just one cycle, injection molding can be a suitable solution. So, regardless of which material you use, the molds can be durable and free of malfunctions over hundreds of thousands of cycles – leaving you with thousands of finished parts.

Mold-Making Leaves a Lot of Scraps

It’s widely known that CNC machines require the input of trained professionals, but they are still sometimes handed off to engineers that have minimal training. Experienced CNC operators typically cover many tasks – including workplace loading, unloading, cycle initiation, monitoring, evaluations, and adjustments – so it is best to employ highly experienced workers who will minimize scrap.

Furthermore, injection molding and mold making produce significantly less scrap compared to other manufacturing processes. The more traditional and, therefore, less-advanced ones often eat away a large chunk of the original material. There are generally four areas of a machine that can ensure low amounts of plastic waste – the runners, gate locations, sprue, and cavity.

Final Words

As is the case with many other manufacturing processes, there are numerous misconceptions that pertain to injection molding and mold making. 

But, if you onboard the right people to do the job, find competent programmers who will know their way around the process, employ reliable machinery – and follow the provided guidelines instead of adopting commonly spread misconceptions — optimizing your manufacturing process will be an easy and straightforward process.