Effect of Cavitation on Plastic.

From a plastics manufacturer’s point of view, one of the most important aspects of injection molding production planning is price. If manufacturing process doesn’t monetize correctly, a product isn’t worth producing. At HTI Plastics, we use a number of different processes and principles to assure optimum possible price with best possible results. One element of production we carefully consider to achieve a satisfactory price is cavitation—the number of cavities producing a part with each press cycle. Our goal is to balance increased cost of tooling a multi-cavity tool with the lower per-part price of multi-cavity projects.

The relationship between cavitation and part price comes down to the number of cavities in the mold. The higher the number of cavities, the lower the individual part price. Increasing the number of cavities lowers the amount of machine time and labor needed to produce each part, and also leads to better use of material. Though multi-cavity molds usually require less production time and smaller amounts of material, the design and initial tooling of a multi-cavity mold cause higher up-front costs. Maintenance costs of multi-cavity molds and processes also typically are higher.

Multiple cavities can be useful in a variety of ways. If a customer wants us to make a high-volume part for an ongoing existing product, a higher number of mold cavities likely will be the most cost-effective solution. However, if a customer is working with us to develop a brand new part for prototyping, a single cavity tool would be a good choice, so we don’t overspend on a mold that might need fine tuning. Once a design is locked in, the part could become a candidate for a higher-cavity tool to help lower costs.

Cavitation and the effect of cavitation on plastic is just one of many things we consider when planning the production process for an injection molded part. Other factors that affect part price include: resin material selection, part size, part features and sometimes secondary operations, such as ultrasonic welding. We always work closely with customers to ensure we understand their needs and use the best processes to help them reach their goals for quality, speed and price.

There are advantages and disadvantages and both are based on the part volumes and the needs of the customer. A single cavity tool is going to have lower initial costs and possibly a reduced lead time to get into production, but will have a higher part price since there is a single cavity and more separate parts to produce. A multi-cavity tool will have increased initial costs because of the design, but a lower part price since there are more cavities to make more of the part at once.

Cavitation is one component of the total cost. What determines the price of cavitation is tooling cost, desired plastic part price and annual volume to ensure the demand of the product can be met. HTI Plastics evaluates all components to ensure our customers get the best product at the best price.

HTI Plastics is a PCE, Inc. company