In this case study detailing the production of test tubes for the medical industry, Uddeholm UK investigates the impact of choosing quality powder for additive manufacturing in tooling for medical parts and devices.
PVC injection mould core with conformal cooling to produce test tubes for the medical industry. Existing tooling produced using powder bed additive manufacturing (SLM) technology.
The material chosen – 1.2709 maraging 300 powder. The core inserts were hardened to 48-50HRC. The total tool life expected and number of production by the manufacturer is 5,000,000 parts per annum.
The result of using 1.2709 additive manufactured printed cores allowed for a conformal cooling design that could not be manufactured in a conventional way. This method allows for uniform cooling of the core during injection moulding production. In return, this offers benefits of lower cycle times and improved cooling efficiency, leading to better part quality.
During production, the limitations of the 1.2709 material began to show. After 400,000 produced parts the 1.2709 core cracked due to corrosion in the cooling channels. This is a typical failure for a material with extremely low corrosion resistance.
Over time, deposits will build up in the cooling channel, especially if the water is left untreated and does not have good filtration. The impact of corrosion in the cooling channels led to bad heat transfer, which in turn made the tool less efficient. The 1.2709 cores were also nickel coated in an attempt to prevent corrosion attack.
Uddeholm AM Corrax® is the pioneering printing material for high demand and efficient designs for mould tooling. AM Corrax® is a corrosion-resistant powder designed for additive manufacturing. It is ideal for conformal cooling and will resist the build-up of deposits in the cooling channels, holding off the corrosion attack.
Uddeholm Corrax® is a Mould steel generally used in the production of PVC building products, therefore, can resist the attack from chloride gasses during moulding. This makes Uddeholm AM Corrax® as a powder the perfect solution, without the requirement for coatings in the cooling channel to prevent corrosive failures.
Uddeholm AM Corrax® produced cores (48-50HRC) showed a significant improvement in tool life with over 780,000 produced parts to date with no maintenance required, and the tool will continue to run.
The result in production savings can be seen above. Uddeholm AM Corrax® does not require Ni coating in the cooling channels and therefore a significant saving can be made upfront. However, the main saving is in the production downtime and reduction in stoppages. In many cases, choosing a more suitable material is an investment worth making.
Taking the next step with a PVD surface coating. There are certain surface coatings that can be applied to upgrade the wear resistance and act as a release agent for the moulded part. This will help to reach the 5,000,000 production with minimum maintenance interruptions.
Contact Uddeholm to find out more about our materials and services for additive manufacturing. Let Uddeholm be your partner in the journey to new tooling possibilities.