35mm Linear Guide Rail

       PEK SDS35 is a 35 mm class high-assembly linear guide rail. It is built for machine tools where load, rigidity, and repeatability are non-negotiable: heavy gantry CNC routers, vertical machining centers with large work envelopes, mold-making machines, and injection molding clamp units that cycle continuously.

       This is a four-row ball bearing guide with 45-degree angular contact. The raceway profile is a Gothic arch, which gives two-point ball contact per row. That means the load spreads evenly across all four ball circuits in every direction-radial, reverse radial, and both lateral directions. Equal capacity. No weak direction.

       The rail is induction-hardened alloy steel, raceway hardness HRC 58–62, precision-ground after heat treatment. The reference edge is ground square to the raceway surface and marked with a "*" for alignment during installation. The block body is case-hardened to the same HRC 58–62. Balls are bearing steel, graded by diameter, and matched at assembly so preload is consistent block to block.

PEK produces the SDS series under an ISO 9001-certified quality management system. Steel is sourced from certified mills with traceable heat numbers. Heat treatment is performed in-house with batch hardness testing. Rail grinding is done on CNC grinding machines with automated wheel dressing and in-process measurement.

Every rail is inspected before packing. Straightness, raceway surface finish, and block sliding fit are checked. Each shipment includes an inspection sheet with the measured values. Blocks are pre-greased and individually sealed. Rails are coated with anti-rust oil and wrapped in VCI paper.

If a rail does not meet specification, it does not ship.

       SDS35 rails are heavy. One meter of rail weighs approximately 6.8 kg. A full kit for a two-meter axis exceeds 30 kg. Use appropriate lifting equipment.

       The mounting surface must be flat within 0.02 mm per 500 mm. If the machine bed has twist or bow beyond this tolerance, the rail will conform to it and the blocks will bind. Surface preparation-machining, scraping, or shimming-must be completed before rail installation begins.

       The 35 mm class is the intersection of capability and practicality. Rails smaller than this become the limiting factor on a production metal-cutting machine. Rails larger than this add weight, cost, and space requirements that are unnecessary for most mid-size CNC applications.

       PEK SDS35 provides the same mounting envelope as Hiwin HGH35 at factory-direct pricing. Standard lengths ship within 3–5 working days. Custom lengths and preloads ship within 7–12 working days.

Q1: Is the SDS35 dimensionally interchangeable with Hiwin HGH35?
Yes. Rail width, rail height, block bolt pattern, rail bolt pitch, and block dimensions are identical. The SDS35 drops into HGH35 mounting positions without modification.

Q2: What is the difference between SDS35 and HGR35?
SDS35 is a high-assembly design. The block body is taller, providing deeper bolt thread engagement and approximately 30% higher stiffness under moment loads. HGR35 is a standard-height design. Rail width and bolt patterns are the same.

Q3: What accuracy grade is required for my application?
N grade (±0.007 mm) for woodworking, plasma cutting, and general automation. H grade (±0.005 mm) for standard metal-cutting CNC milling. P grade (±0.003 mm) for mold-making, precision machining, and applications where part tolerances are tight.

Q4: What preload should I specify?
Z2(medium, zero clearance) is the standard for most CNC milling and general machining applications. Z3 (heavy, negative clearance) is for hard milling, heavy roughing, and applications where maximum rigidity is required. Z1 (light, positive clearance) is for high-speed, light-load axes only.

Q5: What is the longest single rail available?
4000 mm is the standard maximum single-piece length. Longer travel lengths are achieved by butt-joining two or more rails with precision-ground mating faces. The joints are smooth and blocks traverse them without interruption.

Q6: Is a stainless steel version available?
Yes. Martensitic stainless steel rails and blocks are available on request for cleanroom, medical, food-processing, or corrosive environments. Hardness is maintained at HRC 58 or above.

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