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Custom Injection Mold


Everything You Need to Know About Custom Injection Molding

Injection molding is a manufacturing method where a machine injects molten material into a mold to create a custom-shaped product. This method is great for large-scale production of parts that need to be exactly the same. It’s not ideal for single products, but it’s perfect for when you need to make many of the same product.

The entire process of molding can be repeated very fast, typically in less than a minute per part. To operate this fast process, you need an injection mold and a machine.

The Mold

The mold, sometimes referred to as a tool, is a reflection of the concept of the part or product. It is typically constructed in two parts that join in the middle, called the parting line. Inside the mold, the part geometry, texture or polished surfaces are produced in negative form. In this way, when the plastic material flows into the tool and solidifies, it is created into the part.

There’s something more than you will see in the last section. First, molten material must be able to flow into the mold cavity, and there must be an injection system for the material. There are many options depending on desired cycle time, cosmetic needs, and dimensional conformity. The wrong one is difficult to overcome, which is why it is crucial to seek professional advice. In addition, the injection molds include an ejection mechanism to kick the part off the tool once it is opened so that we can be ready for the next process. Third, injection molds also come with a temperature or cooling control system that consists of a series of channels through the mold. In these pathways, a circulating fluid keeps that the mold at an even temperature, so that the process used in the first part is identical to the millionth part.

Most often, the China mold maker is yours to keep for your sole use. Injection molds are a once-off expense, and can make up the majority of your initial project expenses. However, the capabilities of a quality tool can produce consistent, inexpensive parts for years to come.

Injection Molding Machine

An injection mold is a piece made of equipment for capital. Injection molding machines can be designed in many different ways, but there are three most important aspects to consider for your part: size of the mold/tool, shot size and clamping tonnage.

The size of the mold is pretty straightforward the mold should be compatible with the machine, and you need to consider tie bar spacing, as well as the min/max die height. The mold will break along the line of separation and travel in a straight line , held in alignment by four guides, referred to as tie bars. The tool must fit both horizontally and vertically between them. In addition, each machine has a minimum and maximum die height (or thickness) that it is able to take when it opens and closes.

Size of the shot is the second factor to consider as you’ll typically want a machine where the quantity of plastic that goes through your tool is between 20-80% of the barrel capacity. What’s the barrel? The plastic resin, usually in hard pellet form is fed through one the ends of a large cylindrical metal tube called the barrel on the machine for injection. Inside that cylinder lies an auger (or screw) that spins and feeds those pellets around and over the flights of the screw. Once they are at the front, they’ve turned into a melted pile of plastic, waiting to be introduced into the mold in time of the following cycle.

The clamping tonnage is the final aspect to be considered. When the plastic is introduced into the cavity, it is subject to extreme pressure – typically at 250 PSI. When the pressure is applied to the entire surface of your part, it results in an force that is likely to open your mold near the line of separation. To keep it closed the machine uses an amount of clamp tonnage. If you use too little, it will “blow the mold wide open” and cause a separation line flash as a lip of plastic that is where the two mold halves meet. On the other hand when you use too much, it could cause damage to your tool or the machine.

You need to use the right mold and machine to make your product the best it can be. Many businesses save money by outsourcing injection molding to  mold manufacturers in china company that has different machines that can be used for different products.