Injection molding is an essential step in creating precision molded parts, and calculating the necessary injection capacity helps save time and money by ensuring you use only what’s needed.
Through careful calculation of size, shape, machine types and more – coupled with tips to optimize the process along the way – this article will provide readers a foolproof plan for successful injection molding projects.
Determine the volume of the part to be molded
Before calculating injection capacity, the crucial starting point is to use CAD software or manual measurements to pinpoint both volume and melt densities of the part being molded.
It’s critical for accuracy here – any difference in these values can drastically change the results! As an example, we see from Picture that a total volume of 49018.2193 cubic centimeters was determined.
Determine the material density
To ensure accuracy in the injection molding process, it is essential to determine the density of a material before introducing it into the machine.
The specific volume or weight-to-volume ratio can be found on the accompanying data sheet for each material; however if needed, this information may also be obtained through consultation with vendors.
For example when choosing ABS plastic as our selected product (as shown in Picture 2), we knew that its room temperature density was equal to 1.06g/cm³ – an important detail necessary for successful production!
Materials | Nominal | Density |
Polystyrene | PS | 1.05 |
Medium high impact of polystyrene | HI-PS | 1.05 |
Polystyrene acrylic crystal | S | 1.08 |
Acrylobutadiene styrene | ABS | 1.06 |
Styrene-acrylic acid | ASA | 1.07 |
Low-Density Polyethylene | LDPE | 0.954 |
High Density Polyethylene | HDPE | 0.92 |
Polypropylene | PP | 0.915 |
Calculate the injection capacity
Once the details of a part’s size and material are determined, it is possible to calculate how much must be injected into an injection barrel.
By using a simple formula – volume divided by density – you can accurately determine this capacity in grams.
For example, given that a specific component measures out to 49018 cm³ with 1.06g/cm^3 as its material density would require 384g for sufficient injection molding through an injector barrel.
Choose the right injection molding machine
Theoretical injection capacity = (injection molding machine) barrel cross-sectional area × screw stroke.
Injection weight = injection capacity × melt density of raw materials × injection efficiency.
coefficient, a theoretical injection shot weight≤80% of ABS theoretical injection capacity.
So, the right injection capacity of the injection molding machine=384/80%≥480g.
Determine the injection pressure and speed
During injection molding, the pressure and speed used to inject liquid material into a die have an immense influence on the quality of the final product.
To determine these values it is essential to consult with experienced professionals who can provide guidance or conduct tests in a controlled environment.
By taking this extra step during production you can ensure that your finished parts will be accurate and consistent every time!
Consider the cooling time
Another important conversion factor to consider when calculating injection capacity is the cooling cycle time of the material.
Different materials have different cooling times, and it is important to ensure that the material has enough time to cool and solidify before the mold is opened.
If the material is not given sufficient cooling residence time, it can result in defects or other issues with the injection molded parts.
Optimize the injection molding process
For a smoother, more efficient injection molding process with less waste and lower costs, look no further than smaller machines paired with higher-quality materials.
By taking these steps to reduce shrink rate and defects in the output parts during manufacturing, you’ll have greater accuracy across products while still saving on resources used.
Conclusion
Calculating injection capacity is an essential element of successful injection molding. By carefully optimizing the process and considering a variety of factors such as shot size, machine type, pressure levels and cooling time you can ensure that your parts have superior quality while remaining cost-effective in production. In short – getting it right first time means better results!