Choosing the right injection molding machine is of vital importance . The proper machine ensures enough pressure and ram speed, affecting the amount of injected resin and the heat of the barrel heaters. Excessively high temperatures can make it difficult to operate the heater over the long term. Pressure that is too high or too low will deform the machine and prevent it from filling the mold properly. If the capacity of injection molding machine is overlooked, a major problem like short shots can occur. It’s important to use the right injection molding machine for avoiding short shots .

Flow, the movement of molten material throughout the mold cavity, is a key for the molten material to fill the entire mold cavity. It can be helpful to reduce short shots.The material is one of the common causes that affect flow. A material with a high viscosity may flow too slow to fill a detailed mold when it is melted. In contrast, a material with a low viscosity tend to flow into all sections of the mold cavity quickly before cooling. Choosing the material with a reasonable viscosity is an effective way to solve the problem of short shots.

Without enough and proper venting , air traps can be created and may keep the molten material from flowing to all parts of the mold, causing short shots. As for the vents, being deep enough can allow the trapped air and gasses to escape from the cavity, but being not deep enough may lead to flash on the injected part. More venting , ejections pins , or parting line adjustments should be added to let the air get out, minimizing short shots as soon as possible.

Short shots can be affected by the molten material’s temperature. Too low temperature fails to enable the material flow at a speed that can completely fill the injection mold. This results in short shots. However, there will be defects like bubbles when the temperature is too high. It’s a splendid way to prevent short shots by controlling the temperature on the basis of the material and injection molding requirements.

Short shots are related to the injection speed. If the injection speed is too slow, the molten material will fill the mold slowly and incompletely. The material flowing at a low speed is easily cooled, which further reduces its flow performance. Therefore, it fails to fill the entire mold, causing a short shot. In order to deal with this problem, we need to increase the injection speed appropriately. However, the injection speed that is too fast will prevent the material from filling the entire mold cavity. To reduce short shots, the injection speed should be controlled within the appropriate range.

Once the mold design is improper, it can lead to many quality issues on the injection molded part, especially the short shots. Injection molds are designed to produce high-quality parts in high volumes. There are a variety of factors in the process of mold design that can create short shots, including gate size, gate location, part geometry, the type of plastic. If the gate or runner is relatively small, thin, and long, the pressure of the material will be lost excessively during its flow process. This can generate flow resistance, further creating short shots. It is a suggested resolution to design the mold with wider channels or gates, a large nozzle and large sprues and runners for better flow.

Short shots can occur when the injection pressure is too low. Too much plastic sent to the barrel can reduce the injection pressure.The resin pellets are compressed in the process, reducing the pressure that can be applied.The problem of short shots can be solved by adjusting the amount of molten material sent into the barrel during the injection process.

If there is too much lubricant in the raw material formula, and the wear gap between the injection screw check ring and the barrel is large, the molten material will flow back in the barrel. In severe cases, it will cause insufficient material supply, leading to short shots. To handle the issue, the amount of lubricant should be reduced. In addition, the clearance between the barrel, the injection screw and the check ring should be adjusted. Timely maintenance of equipment is also a solution.