3D printing obsolete machine parts

3D printing obsolete machine parts

Being thrifty in the time of turmiol and economic difficulty is imperative to survive as a company. This has been the case with Oyzo manufacturers Giokarinis of Samos. Every summer we return to Samos for around two weeks to return to our roots and the directors of the company are close personal friends. It was over a glass of ouzo that we started discussing that their factory would have to reduce production in as they were having issues with sourcing spare parts. Bearing in mind that the machines are mature and well used, the original manufacturer had sold up and there are capital controls in place, it was almost impossible to source and import parts.

We took on the challenge to design and manufacture some of the more critical wear parts: the bottle neck grippers

First step in the process, after testing the latest batch of ouzo, was to find the least worn gripper to make accurate measurements. This posed a few difficulties as all our metrology tools are kept in the UK, so we did our best. The results were modelled in CAD and the prototype parts were 3D printed our FDM 3D printer and posted back. Turnaround for the prototypes including postage: 7 days. Since we were still on holiday, this required pulling some favours with friends in the UK. Thanks!

Prototype bottle grippers
Prototype bottle grippers

The prototypes were made in PLA (Poly-lactic acid) so did not offer the properties of rubber required. A problem easily solved by gluing some old inner tubes to the area that would grip the bottle necks. Not the final solution, obviously, but good enough for a proof of concept. With the prototype grips installed in the bottling machine we performed a number of trial cycles to identify any need for improvement. We quickly saw that the grips were performing almost perfectly on most of the larger bottles but were not gripping the smaller and thinner bottles as well as they could. This was seen to be the taper on the rubberised side of the grips not being shallow enough.

A second round of prototyping would not be needed however as we were confident in our final CAD models and design. Only issue to solve was the mounting. The original grips were fully moulded around a metal plate tapped with M6 threads. We would need to recreate this mounting and ensure that the new grips would survive the constant use.

The SLA Nylon grippers with threaded inserts
The SLA Nylon grippers with threaded inserts

Once back in the UK we set about sourcing good quality Selective Laser Sintering (SLS) prints of the parts. SLS allows for very dense and smooth parts with layer heights being as thin as 0.06mm! Our material of choice being Nylon for its hard-wearing properties and food safe nature (FDA approved grade thank you sir!).

Threads in nylon would not have been strong enough to withstand use so we used brass press fit inserts. Testing showed that pullout was over 1500N so to our estimate strong enough to last a long time.

A total of 80 pairs of grippers were ordered and delivered to us for inspection.

The client requested that they do the final assembly if we would provide detailed instructions and all the components they would need. So we sent out:

  • 80 pairs of grippers
  • 320 Brass threaded inserts
  • Brush on cyanoacrylate adhesive
  • 3mm thick neoprene rubber sheets
  • Negative former for the rubber

The yellow formers were used to ensure that the neoprene rubber was correctly adhered to the grippers and took the form.

With the parts all shipped the factory was able to put the parts on the bottling machine and resume speedy production of top grade Ouzo.

Grippers with rubber bonded in place
Grippers with rubber bonded in place

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