Machine Comparison
Star Micronics SB-20RII vs Star Micronics SK-51 Type A
Star Micronics vs Star Micronics · Swiss-Type Lathes
Summary
The Star Micronics SB-20RII and Star Micronics SK-51 Type A are both from Star Micronics's swiss-type lathes lineup, making this a common upgrade or lineup decision for shops already invested in the Star Micronics ecosystem. The Star Micronics SK-51 Type A shows specification advantages in 6 categories, though the Star Micronics SB-20RII may still be the better choice depending on your shop's specific needs and the type of work you run. Both machines are proven performers in production environments and represent solid investments for shops in the market for a swiss-type lathe.
Specifications Comparison
| Specification | Star Micronics SB-20RII | Star Micronics SK-51 Type A |
|---|---|---|
| Control | Fanuc 0i-TF Plus | FANUC 32i-B |
| Max Machining Diameter | 20 mm (25/32 in), optional 25.4 mm (1 in) | 51 mm (2 in) ▲ |
| Main Spindle Speed | 10,000 RPM (8,000 RPM with 25.4mm option) ▲ | 5,000 RPM |
| Main Spindle Power | 2.2 kW continuous / 3.7 kW (10 min, 25% ED) | 7.5 kW continuous / 11 kW (15 min) ▲ |
| Sub Spindle Speed | 10,000 RPM (8,000 RPM with 25.4mm option) ▲ | 5,000 RPM |
| Sub Spindle Power | 1.5 kW continuous / 2.2 kW (15 min, 60% ED) | 7.5 kW continuous / 11 kW (15 min) ▲ |
| Coolant Tank | 180 L | 458 L ▲ |
| Machine Weight | 2,000 kg (4,409 lb) | 6,600 kg (14,550 lb) ▲ |
| Dimensions | 2,070 x 1,095 x 1,775 mm | 2,800 x 2,070 x 2,130 mm ▲ |
| Price Range | $90,000 - $150,000 ▲ | $250,000 - $400,000 |
Advantages
Star Micronics SB-20RII
- Superior main spindle speed at 10,000 RPM (8,000 RPM with 25.4mm option) vs 5,000 RPM
- Superior sub spindle speed at 10,000 RPM (8,000 RPM with 25.4mm option) vs 5,000 RPM
- More competitive pricing at $90,000 - $150,000 compared to $250,000 - $400,000
Star Micronics SK-51 Type A
- Superior max machining diameter at 51 mm (2 in) vs 20 mm (25/32 in), optional 25.4 mm (1 in)
- Superior main spindle power at 7.5 kW continuous / 11 kW (15 min) vs 2.2 kW continuous / 3.7 kW (10 min, 25% ED)
- Superior sub spindle power at 7.5 kW continuous / 11 kW (15 min) vs 1.5 kW continuous / 2.2 kW (15 min, 60% ED)
- Superior coolant tank at 458 L vs 180 L
- Superior machine weight at 6,600 kg (14,550 lb) vs 2,000 kg (4,409 lb)
Verdict
The Star Micronics SK-51 Type A edges ahead on specifications in this comparison, particularly in max machining diameter and main spindle power. However, the Star Micronics SB-20RII remains competitive and may be the better choice depending on price, dealer support in your area, or specific workholding and tooling considerations. Both are capable machines — the best decision comes from running your actual parts and evaluating total cost of ownership including tooling, training, and service.