How do you inspect a used kent?
Phase 1: Static Appearance and Basic Inspection (Power Off)
Overall Appearance:
Rust and Maintenance: Inspect the used Kent for severe rust inside and out, especially the guide rails, lead screws, and worktable. Minor wear and scratches are normal, but extensive rust indicates extremely poor maintenance.
Paint and Deformation: Observe the machine body for major dents, cracks, or repair marks, which may indicate that the equipment has been impacted.
Cleanliness: Open the protective cover and check for accumulated debris and oil stains inside. Excessive dirt indicates that the previous user did not pay attention to maintenance.
Nameplate and History:
Check the model number, year of manufacture, and serial number on the nameplate to ensure they match the seller's description.
Inquire about the equipment's usage history (e.g., light-load use in a mold workshop, or heavy-load use on a production line 24 hours a day?).
Accessories and Documentation:
Essential Accessories: Are the magnetic chuck, dresser, balance shaft, grinding wheel flange, various wrenches, adjusting shims, etc., complete? Technical Documents: Operation manuals, circuit diagrams, hydraulic diagrams, and precision inspection sheets are crucial; be sure to obtain them.
Phase Two: Mechanical Precision and Component Inspection (Core Step)
You will need: Dial indicator, magnetic base, level, and inspection bar (if using a universal grinder).
Guideways and Worktable:
Tactile Feel: Touch the guideway surface to check for obvious wear pits or "steps."
Scratches: Inspect the worktable surface. Minor scratches are acceptable, but deep grooves are not allowed.
Leveling: Use a level to initially check the machine bed's levelness; this is the foundation for all precision.
Spindle System (The Heart of the Grinding Machine):
Radial Runout: Place the dial indicator tip on the spindle taper surface and rotate the spindle at low speed, observing the runout value. For ordinary surface grinders, this is typically within 0.005mm; for high precision, it is within 0.002mm.
Axial runout: Place the dial indicator tip at the center of the spindle end face and apply a slight axial force, observing the runout value. The requirements are similar to radial runout.
Abnormal noise and temperature rise: Manually rotate the spindle and listen for any abnormal noises. During subsequent idle operation, check if the spindle temperature rise is normal after half an hour of operation (a warm outer casing is acceptable; if it's too hot to touch, the bearings are faulty).
Feed system:
Leader screw and backlash: Manually crank the handwheel to feel if the feed is smooth and uniform. Use a dial indicator to measure the backlash of the automatic feed; excessive backlash will severely affect dimensional accuracy.
Repeatable positioning: Repeatedly perform fixed-distance feeds and use a dial indicator to check the repeatability.
Hydraulic and lubrication system:
Hydraulic system: Check the hydraulic oil tank and lines for leaks. After startup, observe if the table reciprocating motion is smooth and without "creeping."
Lubrication system: Confirm that the automatic lubrication circuit is unobstructed and that there is a fresh oil film on the guide rails and lead screw surfaces.
Phase 3: Dynamic and Functional Testing (Power-On State)
Electrical Control System:
Basic Operation: Test all buttons, switches, and emergency stop functions for proper operation.
Motion and Interlocking: Test the smoothness of each axis movement and the effectiveness of safety interlock devices (such as door switches).
CNC System (if applicable): Ensure no alarms upon startup, execute axis movement commands, and observe the normal and accurate response.
Key Function Tests:
Spindle Start/Stop: Perform start and stop tests at different speeds to check for smooth operation.
Coolant System: Turn on the coolant pump and check the spray force and for leaks in the piping.
Cheet Function: Test the magnetization and demagnetization functions of the magnetic chuck for proper operation.
