Ready to spruce up your sprues?

If you’re in the world of buying injectionmolded products, then the chances are that you have heard the word ‘sprue’ or ‘runners’ mentioned when doing an on-site visit or discussing the finer details of your project, but do you know what a sprue actually is?

In basic terms, a sprue is a passage or channel through which liquid material is introduced into a mold and connects the pouring basin or hopper to the runner. In many cases it controls the flow of material into the mold.

Why does this matter to me?

There are three main types of sprues and choosing a company such as NS KUNSTSTOFFTECHNIK - CZ who can demonstrate the rationale and take the time to explain the benefits and pitfalls in layman's terms of each, is a surefire way of ensuring success in your project, and critical in ensuring the best output with the least waste from your run.

Cold Sprues are the more “traditional” system and quite simply involve a vertical passage that guides molten plastic through the mold. These are not used as often anymore due to their high number of potential failure points, the fact they need regular maintenance and produce more waste.

A more modern and viable alternative to the cold format is Hot Sprue, or hot runners, which include plastic being heated in such a way that it never solidifies within the runners being used. This allows for fast production and high efficiency.

The third type are hot sprue bushings. These are mostly used as an intermediate step between cold runners and hot runners, as these heated bushings keep plastic hot when it would otherwise cool, but unlike hot runners, they don’t keep runners in a molten state. This format reduces waste and cycle times.

As per every other part of the plastic injectionmolding process, getting this part optimized results in a faster, less wasteful, more reliable and more repeatable process, which is exactly the aim in any mass production.

As specialists in parts for the automotive industry, NS-K’s team of professionals are on hand to answer your questions and walk you, either physically or virtually, through the entire end-to-end process from design to delivery.