Tool costs for the injection moulding of ball bearing cages were 50 times lower than they would otherwise have been - The print2mold process up close

• What was needed: small ball bearing cage series
• Manufacturing method: print2mold (Rapid Tooling)
• Requirements: less time and reduced costs, tool comparable to milled or spark-eroded injection moulding tool
• Material: xirodur® B180
• Industry: household appliances
• Success from the collaboration: more cost-effective, tool produced within three days, extremely high tool detail accuracy

 

The injection moulding tool made of metal was produced with selective laser melting within three days.

The application at a glance:

A ball bearing cage was required for the manufacture of a xiros® polymer ball bearing that would be used in a dishwasher basket pull-out. It was to go into small-series production. But the costs and the time required to produce 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 in the selective laser melting (SLM) process and could be completed within three days. The SLM process enables detailed tool production resulting in precise, high-quality components.

Ball bearing cages with xiros polymer ball bearings

Problem

Production of injection moulds, which are usually spark-eroded or milled, takes several weeks. This long production time is coupled with high costs. The time and money factors were to be significantly reduced in the production of a small ball bearing cage series. Nevertheless, the  variety of materials available in injection moulding was to be maintained in order to avoid any loss in the quality of the polymer ball bearings to be manufactured.

Solution

The igus® print2mold process allowed the speed of additive manufacturing to be used to produce the injection mould. The tool was made within 3 days from the ball bearing cage model with selective laser melting. It was then 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 was around € 450, which was 50 times cheaper 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 EDM and 3D printing were the only possible manufacturing methods for the injection mould.

How does print2mold work at igus®?

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 particularly only suitable for producing prototypes. The selective laser melting (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.

Prototype of an injection mould for a ball bearing cage produced with stereolithography.