A Novel Methodology for Economical Scale-Up of TiO₂ Nanotubes Fabricated on Ti and Ti Alloys

Table 1

Cost analysis of the disc cutting methods. Titanium foils (thickness 0.25 mm; purity 99.5%; 100 × 2000 mm; Alfa Aesar) were used. Staff rate of £20 per hour was considered as a typical wage for technical staff members trained to graduate level in the UK (prices current June 2018).

Disc cutting methods	Method 1 (laser cut)	Method 2 (wire-cut EDM)
Disc cutting device name	iPG laser ytterbium fiber laser 1 kW cutting tool	AgieCharmilles CUT 200 sp EDM wire-cut machine
Associated consumables	2 protecting optics-£142; 2 pressurised argon gas tank-£30	2 EDM brass cutting wires 0.25 mm-£100
Total staff hours (£20/hr)	4 hours-£80	6 hours-£120
Total materials costs	Ti foil of 0.25 × 100 × 2000-£364	Ti foil of 0.25 × 100 × 2000-£364
Gross cost (a)	£616	£584
Total cut specimens (b)	313	450
Actual usable specimens (c)	281	419
Rejection rate ((b − c) × 100/b)	10.2%	6.9%
Estimated cost per usable specimen (d = a/c)	£2.19	£1.39