Model KR-136 polishing machine is specialized pre-processing equipment for rubber, plastic and cable insulation dumbbell test samples. It precisely grinds uneven test specimens to flat, uniform and designated thickness, laying qualified sample foundation for tensile strength, thermal aging, oil resistance and other physical performance tests.

The equipment adopts multi-directional adjustable workbench design; operators can control the horizontal, vertical and front-back displacement of the sample platform via dedicated wrench handles, with smooth feeding and stable grinding effect. The whole machine fully complies with Clause 420.6 of UL1581 industry standard, widely adopted by wire & cable laboratories, rubber material factories and third-party testing institutions worldwide.

Standard Operating Procedures

• Preparatory Work
  Connect power supply and auxiliary water pipe (wet grinding cooling). Select matched fixture according to the width of dumbbell specimen, clamp the test piece and align it to the central position of the workbench, lock the fixture screw tightly.
• Pre-adjust Grinding Gap
  Loosen vertical and horizontal locking handwheels, rotate lifting adjustment knob to move grinding wheel end face to 1mm gap from sample surface, then lock all handwheels. Turn on cooling water valve and power switch to start grinding wheel rotation.
• Formal Polishing Process
  Simultaneously rotate forward and reverse micro-adjustment knobs to lower the grinding head slowly. When abrasive wheel contacts sample surface, swing the grinding head back and forth for uniform polishing, continuously fine-tune downward until the specimen surface achieves full flatness.
• Replace & Grind Reverse Side
  After finishing one side, cut off power and cooling water, turn micro handwheel upward to reset grinding head. Release fixture, flip the dumbbell sample, repeat steps 2–3 to polish the other end surface until both sides meet testing thickness standard.
• Post-operation Arrangement
  Power off the machine, clean residual rubber powder on workbench and grinding wheel, cover protective cover for storage.

Application Scenarios

• Cable & wire manufacturers: UL1581 insulation layer tensile test sample preparation
• Rubber raw material factories: vulcanized rubber tensile, aging resistance test pre-processing
• Plastic compound labs: PVC, TPE, PP dumbbell specimen thickness calibration
• Third-party testing laboratories: standard sample pretreatment for various polymer material performance tests

Product Matching Parts

1. Main machine KR-136 ×1
2. Standard dumbbell sample fixture set
3. Original 36# spare abrasive wheel
4. Operation manual & quality inspection certificate
5. Power cord and cooling water connector accessories