Expert Solutions to Customer Needs

Typical examples of work we do

Engineering Case Studies

Thinking Outside The Box—Nitrogen Freezing Shaft

Our customer had a large rotary valve. The shaft had broken where it had been welded onto the vanes. The most likely cause of failure was weld stress on the shaft at the point it had been welded to the vanes. Simply cutting out the old shaft and welding a new one was not a viable option.

Our Woolston workshop took the complete vane assembly out of the valve and bored a new cavity for a replacement shaft. The new shaft was made fractionally oversized then frozen in liquid nitrogen to reduce its diameter. Once below the size of the machined cavity it was slid into place.

As the shaft returned to normal temperature it expanded and “self locked” into place. The resulting solution provided the customer with a complete and secure shaft replacement without welding.

Adaptability—Machining Large Castings

Our customer had a number of large iron castings needing machining. The castings were approx 500mm long and weighed 40kg. The shape of the castings made them difficult to easily locate in lathes.

Our Woolston workshop manufactured a custom jig to hold and align the castings. The castings could then be machined in our DMG Mori CNC lathe ensuring accuracy and repeatability over a long production run.

High Precision Machining—production machining to tight tolerance

Our customer required a volume of accurate counterweights for one of their manufacturing processes. Made from mild steel these weights were required to be accurate to +/- 0.5 grams.

To achieve this the thickness of each weight had to be within 0.02mm. Over 300 weights were manufactured within these tolerances.

Irrigation Screen repair—Agricultural Service

Our customer had several screens for the irrigation pumps on his dairy farm that had been blocked with silt. The suction from the pumps had collapsed steel framework within the screens. New screens were priced at over $7000 each.

Woolston Engineering stripped out the damaged steel work, built a new framework with stronger section steels, salvaged or replaced the screen mesh and reassembled the whole unit for half the price of a new unit.

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