A bunch of classics at classic flyers

Waikato Innovation Park partnered with Callaghan Innovation to hold the first in a series of practical application workshops last week. The session drew a design engineering audience with an opportunity to hear from Callaghan Innovation material scientists and industry specialists talk about innovative materials and coatings.

Dr Conrad Lendrum and Ruth Knibbe, both Senior Scientists at Callaghan Innovation, talked about commercial examples of how material science is being applied to solve real-world problems. A notable case study was the spontaneous exploding exterior windows of a Wellington office block. Material forensic analysis diagnosed nickel sulphide inclusions formed during tempered glass production. Overtime these inclusions convert to a lower temperature form with a volume increase causing the random breakages.

Page Macrae Engineering and TiDA presented and showcased a range of innovative production processes available in the Bay of Plenty.

Page Macrae Engineering – PVD Coatings

Bruce McLean rattled through an impressive range of coating services they provided by Page Macrae Engineering. Their flagship plasma based surface finishing technology, PVD Coating (Physical Vapour Deposition), applies a coating that significantly improves the strength and durability of a part. High temperature vacuum and plasma sputter bombardment processing atomically bonds a range of coatings to substrates from nanometre to millimetre thicknesses. The hardness increase from PVD is astonishing - about ten times harder than a 3-series stainless steel (hard!).

PVD is being widely adopted to increase part durability. Titanium carbonitride applied to steel drill heads increase hardness (and life) while reducing the friction coefficient (more efficient). Aluminium Titanium Nitriding (AITiN) has been adopted by Katikati based Puma darts to harden their sports dart tips. And by harden I mean 3,600Hv on the Vickers scale with is considerable harder than tungsten carbide at ~2,300Hv.

Some businesses are using PVD for decorative finishing too. The titanium nitride produces a vibrant gold finish and the AITiN provides the desirable titanium grey.

TiDA – Powder Metallurgy

Warick Downing, CEO of Titanium Industry Development Association (TiDA), first spoke about their metal injection moulding (MIM) capability as the most recent addition to TiDA’s powder metallurgy facility in Tauranga.

The process is identical to polymer injection moulding. Finely powdered metals are combined with binding materials then injected under high pressure into cavity tools. Binding agents are removed by solvents leaving the part porous and fragile. The part then requires sintering (thermally treated) in ovens to condense the part up to 99% solid. The binding agent constitutes 30% of the part by volume and shrinkage after debinding is directly correlated. TiDA have run trials on a range of metals including stainless steel. The additional steps required to reach a final part will keep MIM behind polymer injection modelling on the cost front for a while yet. The potential however is vast and looks likely to leapfrog other metal moulding techniques with the promise of high quality surface finishes, complex geometries, and material range. Watch out for early adopters in the healthcare, aerospace and marine sectors.

TiDA are increasing their selective laser melting (SLM) capacity with a new machine coming in May ’13. We used TiDA’s SLM capability last year to manufacture the Young Innovator Award 2012 trophies. 3D parts outputted from CAD files are built up in 1 micron layers from powered titanium. The sintering process fuses the cross sectional layers with lasers to form complete parts over multi-hour programmes.

Tauranga’s Classic Flyers was a great choice of venue. The innovative technology samples amongst the classic aeronautical engineering exhibits in the museum were a salient reminder of production progression. We've come a long way since the balsa frame with stretched cotton skin construction seen on planes serving in the Second World War.