Maintaining a coil feed line for optimum production

A checklist for inspection, maintenance, and troubleshooting

By Kevin Enos

March 14, 2002

Looking for maintenance guidelines for coil feed lines? Find them here, in checklist terms, for coil cars, reels,straighteners, threading tables, and feeds.

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Today's metal stamping facilities are faced with a variety of demands, including increasing production, improving quality, and reducing operating costs. How does a manufacturer attain all of these goals in both good and bad economic times?

Some of the simplest and least expensive ways to meet these demands are to carry out inspections, implement a preventive maintenance program, and perform troubleshooting. This article provides a checklist for maintaining coil feed lines.

Of course, specific maintenance guidelines vary, depending on the equipment's age and manufacturer. For the general purposes of this article, a coil line comprises a coil car, reel, straightener, threading table, and feed. The following checklists can be customized for the equipment's specific features.

GENERAL INSPECTION

A general inspection can help identify potential problems before they become major predicaments.

Coil Car

1. Lift jacks
• Check backlash every six months. If it is more than 50 percent of thread thickness, replace the worm gear.
• Grease lift jacks monthly with extreme-pressure grease.
• Check jack screws every six months for straightness.
2. Gearbox
• Check oil weekly, and change it every six to nine months.
• Grease bearings every 100 hours.
3. Sprocket and chains
• Check chain after the first three months for slackness caused by initial pin wear. Then check it every six months and retighten if needed.
• Check sprocket teeth for uneven wear. If uneven wear is detected, realign the chain and sprocket.
4. Flange-mounted bearings
• Grease every two weeks for normal operation (16-hour day).
• Grease weekly for continuous operation (24-hour day).
5. Hydraulics
• Check daily for leaks. Failure to correct leaks as soon as possible may result in loss of power and create a potential safety hazard.

Reel

1. Mandrel
• Grease wedges weekly.
• Check expansion cylinder daily for leaks. Failure to fix leaks may result in loss of power.
2. Hydraulic motor drive
• Check daily for leaks.
3. Sprocket and chains
• Check chain after the first three months for slackness caused by pin wear. Recheck every six months.
4. Flange-mounted bearings
• Grease weekly.

Hydraulic Power Unit

1. Filter
• Check all hydraulic hoses and fittings for leaks and excessive wear.
2. Tank
• Check tank level weekly and fill as needed.
3. AC motor
• Grease bearing every 12,000 hours. Overgreasing will damage the bearing.
• Check motor temperature daily.

Stock Straightener

1. Straightener head
• Lubricate manually according to the manufacturer's recommended intervals.
• For automatic lubrication, refer to the manufacturer's diagram and recommendations.
2. Chains and sprockets
• Check chain after the first three months for slackness caused by initial pin wear. Then check every six months and retighten if needed.
• Check sprocket teeth for uneven wear at the same time. If wear is detected, realign chain and sprocket.
3. Gearbox
• Change oil after the first two weeks, and then every six to nine months.
• Grease bearings every 100 hours.
4. Belts
• Check for slackness after the first three months and tighten if needed. Check every six months thereafter.
5. Straightener gears
• Check monthly for tooth wear and replace as needed.
6. Flange-mounted bearings
• Grease every two weeks for normal operation (16-hour day).
• Grease every week for continuous operation (24-hour day).
7. Straightener rolls
• Clean weekly, because contaminants on the material may build up on the roll surface. Excessive buildup may cause material marking or improper tracking.
8. Hydraulics
• Check for leaks daily. Failure to correct them as soon as possible may result in a loss of power and create a potential safety hazard.

Threading Table

1. Flange-mounted bearings
• Grease every two weeks.
2. Hydraulics
• Check for leaks daily. Failure to correct them as soon as possible may result in a loss of power and create a potential safety hazard.

Electronic Servo Feed

1. Lift jacks
• Check backlash every six months. If it is more than 50 percent of thread thickness, replace the worm gear.
• Grease monthly with extreme-pressure grease.
• Check jack screws every six months for straightness.
2. Belts
• Check for wear and tightness after the first three months and then every six months thereafter. Retighten if needed and replace if worn.
3. Cluster gear
• Check monthly for tooth wear and replace only as needed.
• Grease weekly with grease recommended by the manufacturer.

PREVENTIVE MAINTENANCE

A preventive maintenance program can help reduce maintenance costs and downtime. An effective program will prevent major equipment problems and will allow stampers to maximize output, minimize cost, and ensure the quality of the parts being manufactured.

Daily Maintenance

• Visually check all systems for proper pressures (see tags for correct pressures).
• Visually check all air lines for leaks and wear.
• Check all hydraulic hoses and fittings for leaks and wear.
• Visually check drive belts for wear.
• Check hydraulic reservoir and add fluid if necessary.
• Visually check all systems for safety hazards.
• Visually check drive chains for proper tension.
• Check straightener's grease reservoir and fill if needed.
• Check automatic grease cup and replace if needed.

Weekly Maintenance

• Repeat daily maintenance.
• Clean air line filter bowls.
• Fill air line lubricator bowl to the indicated level with oil as specified on the tag.
• Repair or replace air-hydraulic leaks, fittings, lines, hoses, valves, and regulators.
• Check belts and tighten or replace as needed.
• Check pulleys and drive components and replace if necessary.
• Check all mounting bolts and tighten if necessary.
• Grease all points as indicated on all equipment tags.
• Visually check chain tightness and adjust if necessary.

Monthly Maintenance

• Repeat weekly maintenance.
• Check oil level in hydraulic reservoirs and add fluid if necessary.
• Check oil in gear reducers and add if necessary.
• Clean all motor cooling fans.
• Check calibration and adjust all readouts.
• Check encoder couplings.

Six-month Maintenance

1. Hydraulic system
• Drain and flush out system.
• Remove front and back covers on the reservoir and clean out.
• Replace covers and install new filters.
• Refill with new oil.
• Repair or replace hydraulic valves that show excessive leakage.
• Repair or replace hydraulic hoses and fittings that show signs of leakage or wear.
• Repair or replace grease or air lines showing signs of leakage or wear.
2. Upper and lower feed rolls
• Replace if finish is worn.
• Replace if flat spots appear on the lower roll.
• Replace bad bearings.
• Inspect coupling and tighten or loosen bolts and shim packs.
• Replace loose or sheared keys.
3. Drivetrain assembly
• Tighten loose belts.
• Replace worn or frayed belts.
• Replace worn pulleys, bearings, and keys.
4. Reel and coil car assemblies
• Follow directions listed previously for six-month maintenance on hydraulic system.
• Drain and flush self-contained hydraulic reservoir (if there is one) and refill with proper oil.

Yearly Maintenance

• Repeat six-month maintenance.
• Check and tighten all electrical connections, terminal strips, relays, and fuses.
• Record amp readings on all motors.
• Check all mount bolts on all equipment.
• Check all motor and gearbox mounting bolts.

TROUBLESHOOTING TIPS

A general knowledge of troubleshooting also reduces downtime. Note that some control panels can describe the type of faults as well as its specific location.

Reel (Uncoiler)

Problem:Material is unwinding off-center.

Solution: Reposition the coil on the center of the mandrel and straightener.

Problem:Expansion does not pick up the coil.

Solution: Rotate the coil shoe to the 12 o'clock position.

Problem:Expansion does not stay constant in manual mode.

Solution: Replace the check valve.

Problem:The coil shoes have lateral movement.

Solution: Check the center guide bolt located in the center of the coil shoe. If the bolt is loose, remove it, add some threadlocking material, and refasten it.

Problem:The mandrel is coasting.

Solution: Increase air pressure if using an air braking system. Turn up the adjustment if using an electrical braking system.

Problem:The restrictor arm does not stay up.

Solution: Replace the check valve on the cylinder because it is leaking either internally or externally.

Problem: The double end reel will not rotate.

Solution: Make sure the restrictor arm is in the up position.

Solution: Make sure that the shot pin is retracted.

Solution: Verify that the peeler blade is retracted.

Solution: Verify that the peeler table is down.

Stock Straightener

Problem:The material will not track on-center.

Solution: Position the straightener on the center of the coil and reel.

Solution: Verify that the stock guides are on the center of the straightener and reposition them if required.

Solution: Verify that the pinch rolls are parallel and realign them if required.

Solution: Verify that the upper straightening rolls are parallel.

Problem:The motors on the motorized head adjust trip out.

Solution: Tighten torque limiters to keep them from slipping.

Solution: Make sure the straightener head is not penetrating the material too far.

Problem:The material has scratches or marks on the surface.

Solution: Clean buildup from the pinch rolls or straightener rolls with solvent or an emery cloth.

Problem:The rolls are walking to one side.

Solution: Make sure the drive chain is not too tight.

Solution: Verify that the pinch rolls are parallel and adjust if necessary.

Solution: Check the stock guides and the coil's position on the reel to make sure it is on the center of the rolls.

Problem:The drive chain keeps breaking.

Solution: Make sure the sprockets have not moved, and retighten the set screws if necessary.

Solution: Make sure that the roll penetration is commensurate with the material.

Sonic Loop Control

Problem:The material does not stop running.

Solution: Recalibrate the device and evaluate the environment for excessive noise and sudden temperature changes caused by open doors and so forth. If the problem cannot be resolved, contact the manufacturer.

Problem:Material from the straightener does not keep up with the feed.

Solution: Adjust the speed from the sonar control.

Photoelectric Loop Control

Problem:The material does not stop running.

Solution: Check the photo-eyes for cleanliness before the start of each shift.

Solution: Reset the eyes if an object strikes them.

Problem:The material from the straightener does not keep up with the feed.

Solution: Check the voltage output relative to the straightener drive and adjust as needed.

Rack-and-Pinion or Electronic Feed

Problem:Feed lengths are inconsistent (rack and pinion).

Solution: Replace the brake lining or readjust the pads.

Problem:The amount of backlash between the rack-and-pinion gears is too great.

Solution: Reshim the rack in the rack housing to tighten the backlash.

Problem:Keys are loose.

Solution: Check all keys in rolls and couplings for loose keys and replace as needed.

Problem:Backlash is occurring in the roll gear.

Solution: Replace the roll gears if the teeth are worn.

Problem:Backlash is occurring in the clutch (rack and pinion).

Solution: Flush and refill the clutch, or rebuild or replace if necessary.

Problem:Roll lift timing is incorrect.

Solution: Retime the lifters and check the cam switch.

Problem:Backlash is occurring in the crankpin and adjusting screw.

Solution: Replace the crankpin and adjusting screw.

Problem:Backlash is occurring in the crankpin and adjusting screw.

Solution: Check the roll surface for wear. If the chrome blast finish has worn off, resurface the rolls.

Solution: Increase the upper roll pressure by tightening the springs or increasing air pressure.

Solution: If all mechanical possibilities check out appropriately, consult the manual supplied with the drive. On an electronic feed, a short feed length should appear as a fault in the drive diagnostics.

Problem:Backlash is occurring in the crankpin and adjusting screw.

Solution: Verify that the stock guides are not off-center; if they are, recenter them.

Problem:Backlash is occurring in the crankpin and adjusting screw.

Solution: Make the roll parallel, and make sure the upper roll moves freely up and down.

Solution: Make sure the roll pressure is equal on both ends of the rolls, whether it is air or spring hold-down. If the pressures are not equal, adjust them accordingly.

Problem:Backlash is occurring in the crankpin and adjusting screw.

Solution: Verify that the coil is located properly on the reel. If the coil is not on the centerline, adjust it.

Solution: Verify that the reel and straightener are located on the centerline of the press, and relocate them if necessary.

Problem:Backlash is occurring in the crankpin and adjusting screw.

Solution: Change the coil.

Implementing an inspection and maintenance program can be the simplest way to keep costs down in any economic condition. Be sure to coordinate with the equipment manufacturer for your system's specific needs.