Injection Molded Plastic Housing for 1 Channel EMG Sensor

Vincent Systems GmbH

The company specializes in robotic hand prostheses end-to-end development and production. Since 1998 Vincent Systems continuously and patiently was developing robotic hand prostheses.

Robotic hand prototype

Beginning with thin foil soft robot hand with 5DOF and ending with modern commercialized and daily-used worldwide product. This company is a true lives changing global innovator.

Robotic hands produced by Vincent Systems are controlled by variety of sensors interacting with human body. We are proud that Micromolds was selected to make plastic cases for one of them, even though it took us long time to prove credibility for such project.

Bionic hand

We are used to long term partner selection processes:

“Lead conversion time to customer usually varies between 1-3 months” – says CCO Dominykas

But this one took us truly long time. Whole five months were already passed since Vincent contacted us first time. To our surprize, the order was made within few days when decision was confirmed. The company was working on new designs and it took them nearly 5 months do develop them.

Design for Manufacturing (DFM) – mouldability analysis

After signing quality assurance agreement, we proceeded further with the DFM. Even though it was spent a lot of time on designing the part we still had to do some minor changes so the part could be mouldable. All designs can look nice and be created to function properly, but not all of them can be technological – manufacturable.

Design of new plastic case for sensor

We had to add some inner radiuses as those are unavoidable due to the CNC mills used. We also had to set ejector marks and injection gates of the part.

Tooling - mold making

The surface of the part had to be EDM machined and have a mate look. Thus we also had to design electrodes for EDM machining and do the EDM. Since the plastic case was assembled from 2 pieces, one side of it had hooks that snap fit with the other. To form those undercuts we had to use a metal 3D printed inserts. The parts were small enough to fit in our aluminium 1+1 micro mould thus we CNC machined 2 cavities in it and did EMD machining to finish the surface.

Samples injection moulding

We understand that designing something new – something that was never created before is enormously challenging but also very satisfying. However, this satisfaction comes at some cost – which is trial and error. Errors can occur not only due to the faulty design but also due to the errors made by moulder. It is important to understand that sometimes there is practically impossible to tell which party was wrong or right. In such cases it is best when both contractor and subcontractor can remain solution focused which happened to our company and Vincent Systems.

Since the housing was very small and with thin walls, too tight fit during the assembly resulted in slight deformation of the whole plastic case which caused inconsistent part match at the corners. Both companies agreed that the distance could be decreased to loosen the fit so the deformation would be eliminated. When the mould modification was done the new samples were much better and reached the demanded quality of the customer.

Assembled plastic case with defects

The results

After the first batch was moulded we did a careful visual inspection of every piece. We also did an assembly to check if the parts match correctly and there are no deviations. The first batch was shipped on time and reached the client successfully. We are truly happy that we could contribute to such an innovative project developed by such a reputable company.

plastic case other half molded in low volume batch
plastic cases molded in small series