Tool costs for the injection molding of ball bearing cages were 50x lower than they would have been

• What was needed: Small series of a ball bearing cage
• Manufacturing process: print2mold (Rapid Tooling)
• Requirements: less time and reduced costs, tool comparable to milled or eroded injection-molding tool
• Material: xirodur B180
• Industry: Household appliances
• Success through cooperation: More cost-effective, production of the mold within three days, maximum level of detail of the mold

A ball bearing cage was required for manufacturing a xiros polymer ball bearing that would be used in a dishwasher pull-out basket. It was to go into small-series production. However, the costs and time required to make the injection-moulding tool were very high. These disadvantages were counteracted with the help of the print2mold process.

The tool was manufactured from tool steel with SLM (selective laser melting) and could therefore be completed within three days. The SLM process enables detailed tool production, resulting in high-quality and precise components.

It takes several weeks to produce injection molds, which are usually eroded or milled. This long time period is coupled with high costs. We wanted to reduce the time and money required significantly when producing a small ball bearing cage series.

Nevertheless, we intended to maintain the variety of materials available in injection molding so as to make sure that the quality of the polymer ball bearings to be manufactured was not compromised.

The igus print2mold process uses the speed of additive manufacturing to produce the injection mould. The tool was made within three days from the ball bearing cage model with SLM. After that, it was used to manufacture the ball bearing cage from the iglidur material best suited to the polymer ball bearing application. The cost of the prototype tool amounted to around €450, which was 50 times more cost-effective than the later series tool. This cost advantage can be explained by the fact that the special shape and size of the ball bearing cage made milling or grinding almost impossible, which is why spark-eroding and 3D printing were the only possible manufacturing methods for the injection mould.

Unlike milling and spark erosion, additive manufacturing involves the deposition of material. The process's resource-conserving approach not only favours production speed, but also allows for different geometries that would not be feasible with conventional production methods. There are two processes that can be used to print injection moulds in 3D: the SLA process (stereolithography) is only suitable for producing prototypes. The SLM process is used to make tools from metal, primarily for small series and test phases of up to 25,000 pieces. In addition to the rapid production of the injection mould, the print2mold process also offers great advantages when it comes to material selection. More than 60 iglidur plastics are available; with them, almost all requirements for a sliding application can be met.