8 ways to keep your shear in top shape

THE FABRICATOR® AUGUST 1999

April 10, 2001

By:

Improving uptime and reducing maintenance when using shears for high production could mean following a few key steps.

Shears are common pieces of fabricating equipment that can be found in many metal forming plants. From tube mills to small fabricators, the shear is one of the most critical and diverse tools used in metal fabricating.

Varying in size from small hand-held metal shears and foot-operated trim shears to high-production in-line flying cutoffs, the modern metal shear has replaced the saw as the machine of choice for high-production metal cutting.

This article addresses improving uptime and reducing maintenance when using shears for high production.

The following tips are from shear users and rebuilders who found success when they implemented them.

Tip No. 1 — Understand Your Machine

It is important to understand the function, design, and operation of your machine. The main cause of shear failure is overloading it beyond the OEM's parameters. Shears are designed to cut metal of an established thickness and width. When these limits are exceeded, damage occurs.

In addition to following the OEM's load recommendations, normal adjustments should be made regularly, and maintenance schedules and service requirements should be followed carefully.

Misusing lubricants and other fluids also causes damage. Lubricants and fluids must be used as specified by the OEM.

Tip No. 2 — Perform and Document Regular Inspections

A regimented inspection schedule should be posted and adhered to. Areas that should be inspected include the shear's ability to execute all functions of operation; on mechanical machines, all bearings should be checked for lost motion and wear; and all emergency and safety functions should be examined.

Tip No. 3 — Review Documentation

After regular inspections are performed and documented, the data should be reviewed systematically. This review can reveal wear patterns, the potential for accidents, and nonconformance so that repairs can be made.

Documentation and analysis are the basis of preventive maintenance. With this information, a clearly laid out maintenance plan can be prepared, eliminating most emergency repairs.

Tip No. 4 — Set the Blade Properly

Setting the shear blade properly is key to extending blade and machine life. Setting the proper clearances for blade cutting affects the drive, ram, tooling, and cut quality. Additionally, before setting the blade, the blade seat should be checked for flatness and to ensure that the tooling is seated properly to eliminate blade chipping caused by shifting during cutting.

If the clearances are too tight, improper cutting action occurs because the metal jams between the blade and the machine. If the blades have no clearance, they will break. When clearances are too loose, the blade acts as a hammer that applies multiple forces to the machine's components, causing premature wear and failure.

Tip No. 5 — Maintain Correct Gib Clearance

Setting and maintaining proper gib clearances increase tooling life and machine uptime. The gibs maintain proper guiding action of the ram and attached tooling. If the clearances are not maintained, the same problems occur as those that take place when the blade clearances are ignored.

Tip No. 6 — Isolate and Level the Machine

Leveling a shear and isolating it from vibration are critical to proper operation. The proper selection and installation of isolation pads can increase tooling life and shearing speed, decrease vibration, improve foundation life, reduce noise, and eliminate shear frame distortion.

Using today's isolators, machine leveling can be done in less than a half hour. Making sure that the shear is level eliminates the twisting action that can destroy a shear.

Tip No. 7 — Follow a Basic Maintenance Plan

The following parts of a shear require regularly scheduled maintenance:

1. The air system should be maintained properly to ensure that the air is clean. All regulators must be set so that they are operating correctly. Maintaining the regulators helps the pneumatically actuated mechanisms to function properly.

2. The lubrication system must be cleaned, filled, and properly filtered. Broken, kinked, or twisted lines must be replaced. Each point must be disconnected and examined to determine if the lubrication is reaching its destination. Sumps and reservoirs should be routinely emptied, cleaned, and refilled.

3. The machine clutch and brakes must be examined for proper lining thickness, clearances, and signs of failure. Worn linings must be replaced immediately. Overtravel beyond the machine builder's specifications must be adjusted and/or corrected upon inspection.

4. Counterbalance cylinders should be tested and reworked at the first sign of air leaks or failure. A counterbalance cylinder that has the proper action ensures the longevity of all working components of the shear and its tooling.

Tip No. 8 — Make Repairs as Soon as Possible

When damage, wear, or out-of-adjustment conditions are found, the shear should be immediately repaired or adjusted. Most catastrophic failure is caused by putting off simple repairs. Addressing repairs quickly is almost always less expensive than the cost of correcting the damage that can take place when repairs are ignored or put off. Additionally, operator safety depends on timely repairs.

Keeping the shear productive can be accomplished by performing these simple tasks. When a shear is maintained properly, replacement costs and catastrophic failure are avoided.

Tip No. 4 — Set the Blade Properly

Setting the shear blade properly is key to extending blade and machine life. Setting the proper clearances for blade cutting affects the drive, ram, tooling, and cut quality. Additionally, before setting the blade, the blade seat should be checked for flatness and to ensure that the tooling is seated properly to eliminate blade chipping caused by shifting during cutting.

If the clearances are too tight, improper cutting action occurs because the metal jams between the blade and the machine. If the blades have no clearance, they will break. When clearances are too loose, the blade acts as a hammer that applies multiple forces to the machine's components, causing premature wear and failure.

Tip No. 5 — Maintain Correct Gib Clearance

Setting and maintaining proper gib clearances increase tooling life and machine uptime. The gibs maintain proper guiding action of the ram and attached tooling. If the clearances are not maintained, the same problems occur as those that take place when the blade clearances are ignored.

Tip No. 6 — Isolate and Level the Machine

Leveling a shear and isolating it from vibration are critical to proper operation. The proper selection and installation of isolation pads can increase tooling life and shearing speed, decrease vibration, improve foundation life, reduce noise, and eliminate shear frame distortion.

Using today's isolators, machine leveling can be done in less than a half hour. Making sure that the shear is level eliminates the twisting action that can destroy a shear.

Tip No. 7 — Follow a Basic Maintenance Plan

The following parts of a shear require regularly scheduled maintenance:

1. The air system should be maintained properly to ensure that the air is clean. All regulators must be set so that they are operating correctly. Maintaining the regulators helps the pneumatically actuated mechanisms to function properly.

2. The lubrication system must be cleaned, filled, and properly filtered. Broken, kinked, or twisted lines must be replaced. Each point must be disconnected and examined to determine if the lubrication is reaching its destination. Sumps and reservoirs should be routinely emptied, cleaned, and refilled.

3. The machine clutch and brakes must be examined for proper lining thickness, clearances, and signs of failure. Worn linings must be replaced immediately. Overtravel beyond the machine builder's specifications must be adjusted and/or corrected upon inspection.

4. Counterbalance cylinders should be tested and reworked at the first sign of air leaks or failure. A counterbalance cylinder that has the proper action ensures the longevity of all working components of the shear and its tooling.

Tip No. 8 — Make Repairs as Soon as Possible

When damage, wear, or out-of-adjustment conditions are found, the shear should be immediately repaired or adjusted. Most catastrophic failure is caused by putting off simple repairs. Addressing repairs quickly is almost always less expensive than the cost of correcting the damage that can take place when repairs are ignored or put off. Additionally, operator safety depends on timely repairs.

Keeping the shear productive can be accomplished by performing these simple tasks. When a shear is maintained properly, replacement costs and catastrophic failure are avoided.



Robert Kotynski

Contributing Writer

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The FABRICATOR® is North America's leading magazine for the metal forming and fabricating industry. The magazine delivers the news, technical articles, and case histories that enable fabricators to do their jobs more efficiently. The FABRICATOR has served the industry since 1971. Print subscriptions are free to qualified persons in North America involved in metal forming and fabricating.

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