Plastic injection machine Injection Volume Calculation Determining Proper Injection Volume

Injection volume calculation is a metric that must be faced daily in plastic injection machines. It is essential for injection molding because it determines the material required to fill the mold cavity and produce the desired part. The correct injection volume ensures that the mold is filled otherwise, it will affect the consistency of the product size produced. In this article, we will share the calculation process for the injection volume of a plastic injection machine.

Factors affecting the calculation of injection volume of plastic injection machine

Several factors affect the calculation of the injection volume of a plastic injection machine. The first is the injection volume. The injection volume refers to the volume of material injected into the mold cavity in a single injection. The size and geometry of the molded part, along with the required part weight and dimensions, determine it.

The maximum volume of material that can be injected per injection is determined by the screw diameter and stroke length. Injection pressure plays a vital role in determining the flow behavior of the molten material during the injection process. Injection speed refers to the advancement of the screw and injecting material into the mold shape. The cavity’s velocity can affect the injection volume and molding process when adjusted to the injection speed. The design and geometry of the mold cavity, runner system, and gate configuration affect the flow path and distribution of material during the injection process.

What will happen if the injection volume of the plastic injection molding machine is not suitable?

When a plastic injection molding machine has insufficient injection volume, it may result in incomplete filling of the mold cavity, resulting in short shots or incomplete parts. This can also occur when air becomes trapped in the mold cavity during filling, causing bubbles or voids within the part. This can weaken the structural integrity of the part and compromise its performance. Insufficient injection volume of plastic injection molding machines can also cause sink marks on the surface of molded parts.

Sink marks occur when a material shrinks unevenly as it cools, causing depressions or dents to form on the part’s surface. This affects the appearance and decorative quality of the part, especially in visible areas. This can also cause the part to warp or deform during the cooling and demolding process, affecting the part’s fit, function, and assembly compatibility.

Steps to Calculate Injection Volume of Plastic Injection Machine

Calculating shot volume for a plastic injection machine involves several steps, starting with understanding the material requirements for the molded part, including the type of plastic material, required part size, weight, and geometry. Then comes the calculation of the shot size needed to fill the mold cavity and produce the desired part. Factors such as the volume of the mold cavity, part geometry, and material shrinkage determine the shot size. Next is determining the density of the plastic material used in the injection molding process, using the density of the material to convert the calculated shot size from volume to weight. Use the formula: Injection Weight = Injection Size × Material Density. This calculation gives the weight of material required for each shot.

The importance of appropriate injection volume

Proper injection volume in plastic injection molding machines ensures quality, even filling of the molding process, and can reduce the risk of short shots, voids, or incomplete parts. The consistent filling also helps maintain part integrity, surface finish, and dimensional accuracy. Manufacturers can reduce material consumption, lower production costs, and improve overall efficiency by accurately metering the material required for each shot. The correct shot size also ensures that molded parts meet design specifications, minimizing variations and deviations in size, shape, and geometry.

Tools and resources for calculating injection volume

Calculating injection volume for a plastic injection molding machine requires using various tools and resources, including specifications and technical documents provided by the manufacturer. This includes information on the machine’s shot volume, screw diameter, stroke length, and maximum injection pressure, which are critical parameters for calculating shot volume. We must also reference mold design and specifications to determine mold cavity volume, runner system, and gate configuration. Another option is to use the online injection molding calculators and tools available on various websites and software platforms. These calculators allow users to enter parameters such as mold cavity volume, material density, shot size, and processing conditions.


Shot volume calculation is fundamental to plastic injection molding but can impact part quality, consistency, and cost-effectiveness. By understanding the factors that influence injection size, following a systematic calculation process, and utilizing the appropriate tools and resources, manufacturers can confidently determine the right shot size for their molding application. Proper calculations ensure the mold is filled completely and consistently, producing high-quality parts that meet customer requirements and expectations.

Hashtags: #Plastic #injection #machine #Injection #Volume #Calculation #Determining #Proper #Injection #Volume

2024-04-15 08:24:05

Stay Tuned with for more Tech news.

Related Articles

Back to top button