CNC Vertical Machining Centers
PMI MSB roller guideways on X/Y axes with MSB-T carriages for high cutting rigidity. FSI C3 ground ball screws on all three axes. A proven combination in the Taiwanese VMC builder ecosystem.
About PMI (Silvertech)
PMI Group (Precision Motion Industries), known in international markets as Silvertech, is a Taiwan-based linear motion manufacturer with a strong focus on precision and rigidity. Founded by engineers with deep experience in the machine tool industry, PMI has developed a reputation for producing guideways and ball screws that deliver class-leading accuracy stability under load — a critical factor for CNC machining applications.
PMI's MSA ball guideway series and MSB roller guideway series are widely specified by Taiwanese and Chinese CNC machine tool builders, competing directly with HIWIN in the same market segment. PMI's ball screw manufacturing process — from steel selection through grinding and assembly — is vertically integrated at their Taichung facility, ensuring consistent quality control across the entire product chain.
Core Product Lines
MSA-A / MSA-E / MSA-S / MSA-L
Ball Linear Guideways
Four-row ball circulation guides in flange, slim, high-profile, and low-profile carriage styles. Sizes 15-65. Standard (N), high (H), and precision (P) accuracy classes.
Applications: CNC machining centers, EDM machines, industrial robots, measurement equipment
MSB-T / MSB-E / MSB-S
Roller Linear Guideways
Cylindrical roller recirculating guides with high static/dynamic load capacity and superior moment stiffness. Sizes 25-65 for heavy-duty applications.
Applications: Heavy CNC lathes, gantry mills, injection molding machines, press lines
FSI / FDI / FDC / OFV / OFI
Precision Ball Screws
Ground (C3/C5) and rolled (C7) ball screws with single (FSI), double (FDI), and double-cylinder (FDC) nut configurations. Optional cooling (OFI) and high-speed variants.
Applications: Machine tool axes, robotic arms, electronic assembly, semiconductor equipment
KM / KA / KC
Linear Actuator Modules
Aluminum-based single-axis modules combining PMI guideway and ball screw. KM series with built-in motor mount for direct coupling. Stroke up to 1,250 mm.
Applications: Automated inspection, dispensing, material handling, teaching equipment
Technical Parameters
| Parameter | Value |
|---|---|
| Accuracy Grade (JIS B 1192) | C3 / C5 / C7 |
| Dynamic Load Range (Guideways) | 3.5 kN - 340 kN |
| Rail Width Range | 15 - 65 mm |
| Operating Temperature | -10°C - +80°C |
| Friction Coefficient | 0.003 - 0.006 |
| Maximum Velocity (Ball Guides) | 2.5 - 5.0 m/s |
Key Applications & Operating Conditions
Precision Grinding Machines
MSA-P accuracy class ball guideways with reduced waviness raceways for surface and cylindrical grinding applications where surface finish quality is the critical output specification.
EDM (Electrical Discharge Machining)
MSA-S narrow-type guides for wire-cut and die-sinking EDM machines. PMI's tight accuracy stability under thermal cycling is important for maintaining electrode positioning across long-duration burns.
Automated Optical Inspection (AOI)
KM linear modules with MSA-E guides for PCB inspection gantry systems. Combined accuracy and smoothness for high-resolution camera scanning at 0.5-1.0 m/s.
Cross-Brand Compatibility Reference
PMI MSA ball guideways are dimensionally interchangeable with HIWIN HG series in most sizes (15-45), and both follow ISO 12090-1 for bolt pitch and rail width. PMI and HIWIN are frequently cross-shopped in the CNC machine tool segment — PMI typically offers marginally better rigidity specifications, while HIWIN has wider distribution and faster lead times. For ball screws, PMI FDI (double nut) is comparable to TBI MOTION's SFI series in the C5 accuracy range.
Common Faults & Maintenance
- MSA guideway precision degradation: Inspect all carriage mounting bolts for proper torque. PMI guideways require periodic accuracy verification using a dial indicator along the full stroke. If parallelism error exceeds 0.02 mm over 1,000 mm, the rail mounting may need re-alignment or re-grinding of the mounting surface.
- Ball screw thermal growth causing position drift: For long-stroke, high-speed applications, consider upgrading to PMI's OFI (Oil Flow Internal) hollow-shaft ball screw with coolant circulation. This reduces thermal elongation by 50-70% compared to solid screws. Alternatively, implement software-based pitch error and thermal compensation in the CNC controller.
- MSB roller guide noise under acceleration: PMI roller guides require more frequent lubrication than ball guides due to the higher contact stress. Reduce the re-lubrication interval by 30-50% compared to the standard PMI schedule. Verify that the grease type matches the application speed — lithium grease with base oil viscosity 100-150 mm²/s is recommended for MSB guides.
Frequently Asked Questions
Q1: How does PMI compare to HIWIN for CNC machine tool applications?
PMI and HIWIN are the two leading Taiwanese linear motion brands in the CNC segment. PMI typically offers 5-15% higher static rigidity in equivalent-size roller guideways (MSB vs QH), while HIWIN has broader availability and 1-2 week faster standard lead times. Both offer C3/C5 accuracy and comparable pricing. Many Taiwanese VMC builders qualify both brands and select based on project lead time.
Q2: What accuracy class should I specify for a CNC milling machine?
C3 is the standard for CNC milling machine ball screws — delivering ±12 µm cumulative lead error per 300 mm. For guideways, specify MSA-P (precision) or equivalent H accuracy class for the X/Y axes and standard N class for the Z axis. For high-speed machining centers above 15,000 rpm spindle speed, consider C1/C2 specifications with cooling options.
Q3: Are PMI products available in corrosion-resistant versions?
Yes. PMI offers the MSA series with hard chrome plating and stainless steel carriage options. For food and medical applications, the MSA-SUS series uses martensitic stainless steel. Contact thk@591888888.com for the full corrosion-resistance options catalog.
Q4: What is PMI's warranty policy on linear guideways?
PMI provides a 12-month warranty from shipment against manufacturing defects when products are used within their rated specifications. The warranty covers replacement of defective components but does not cover damage from contamination, inadequate lubrication, or overload conditions above the rated dynamic capacity. Extended warranty (24 months) is available for OEM volume contracts.