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Medical Pump Case Study

Case Study: A custom solution for material removal and tin plating on a medical pump component

A customer manufactures a medical flow-through valve which contains a pump that regulates the flow rate of fluid drip on an intravenous line. Inside the valve, a metal disc makes contact with the pump, which is part of an adjustable-speed pulsating mechanism. The entire valve unit must be disposable, as every fluid change would require a new valve for sanitary and infection control reasons.

The precision stamping challenge

Blanks made of 1008 cold rolled steel 0.040” thick were used to stamp 0.60” diameter discs. The stamping challenge was to reduce thickness of the steel disc to 0.020”, leaving an inner circle of 0.50” in diameter.

In addition, an electro deposited 0.0001” – 0.0002” as per MIL-T10727A Type 1 tin plating was specified, with no discoloration and no distortion on the final component.

Finally, meeting the required flatness tolerance of 0.0001” resulted in the plated discs sticking to each other.

CEP’s solution

The first operation in the progressive stamping process was to push the material for the 0.50” diameter circle below the strip. This resulted in a half-cut on the outer diameter. A ring 0.020” deep was then coined from the die side to achieve the correct thickness. The blank was then flattened and pushed through the die.

During plating, media was added to the plating barrel to reduce parts sticking to each other.

The outcome

As a result of this customized process, CEP provided the customer with parts to print at a minimum volume of 20 million parts annually.

Process details

  • Equipment used: Bruderer 30T
  • Part Dimensions: 0.600” outside diameter with a 0.500 inner raised diameter, 0.040” thickness through the raised portion and 0.020” thickness through the outer ring
  • Tightest tolerances: flatness to 0.001”
  • Material used: CRS 1008 040 temper DQ RB 50 max
  • Plating Finish: electro deposited 0.0001 – 0.0002 as per MIL-T10727A TYPE 1 tin
  • Industry: disposable medical
  • Volume: in excess of 20 million pieces annually