- The height A of little part is much thicker than the height B of its pedestal
- We need a prefect solution for the joint of little part and its pedestal
- Mirror polishing for the external surface without bending the slim pedestal
The related processes: MIM (metal injection molding), CNC machining
When we got the drawing of this switch cover from our customer, we offered three solutions to make the product: 1, to make the whole part by CNC machining 2, to make the whole part by MIM 3, to make the pedestal by CNC but to make the little parts by MIM.
Option 1: It would waste too much materials, because the height B of little part is much thicker than the height B of its pedestal, we’ll have to remove the most of the materials. And the structure of its design makes it very hard to cut grooves on the internal side of little parts, that’s why this option is failed to be chosen.
Option 2: It is also not a prefect idea, because the pedestal is too large and slim for MIM process, it might bend slightly after sintering, we didn’t want to waste any time and cost on the choice uncertain.
Option 3: To be honest, this product is mainly formed by a pedestal and some little parts stand on it. Technically speaking, the pedestal is large and slim, which is suitable to be made by CNC machining, while those little parts are small with curved design on the external side and tiny grooves on the internal side, but we’ll solve this tough problem by MIM, after all MIM process was invented to make those complex small parts.
But there is still a problem when we decide to choose option 3, how do we connect those little parts with the pedestal? We initially focus on welding, we had tried laser welding and cold welding, but no matter what welding method we use, there are also welding marks. After trying many times, we decided not to choose welding as the method to connect them. Finally, we completed the whole part by using super glue specially made to connect metal parts. We wipe glue marks before it dries, and the whole part looks just like a single unit, and it’s strength is better than welding!
Speaking of mirror polishing, we also prepared a special made tool to hold the product when it was being polished.