Grinder Safety – Grinder Safety – Understanding Safeguarding Standards for Bench and Pedestal Grinders
Because grinders are everyday equipment in workplaces nationwide, many workers become complacent about their hazards. However, grinders are one of the most frequently cited machines during OSHA safety inspections. Rockford Systems, LLC, a premier provider of machine safeguarding products and services, offers this primer on grinder safety regulations to help prevent accidents and fatalities.
First off, it is important to be fully versed in the regulations that outline safe grinder installation, maintenance and operation. The workplace regulations that apply to grinders are OSHA 29 CFR SubPart O 1910.215, a “machine specific” (vertical) regulation with a number of requirements, which if left unchecked, are often cited by OSHA as violations. ANSI B11.9-2010 (Grinders) and ANSI B7.1 2000 (Abrasive Wheels) also apply. Carefully review these sets of regulations before operating any grinding machinery.
Grinder Safety – Work-Rests and Tongue-Guards
OSHA specifies that work-rests be kept adjusted to within 1/8-inch of the wheel to prevent the workpiece from being jammed between the wheel and the rest, resulting in potential wheel breakage. Because grinders run at such high RPM, wheels actually explode when they break, causing very serious injuries, blindness and even death. In addition, the distance between the grinding wheel and the adjustable tongue-guard — also known as a “spark arrestor” — must never exceed 1/4-inch. Because the wheel wears down during use, both these dimensions must be regularly checked and adjusted.
Grinder safety gauges can be used during the installation, maintenance, and inspection of bench/pedestal grinders to ensure work-rests and tongue-guards comply with OSHA’s 1910.215 regulation and ANSI standards. To do so, wait until the wheel has completely stopped and the grinder is properly locked out before using a grinder safety gauge. Grinder coast-down time takes several minutes, which may tempt an impatient employee to use the gauge while the wheel is still rotating. This practice is very dangerous because it can cause wheel breakage.
Other advice: where grinders are concerned, personal protective equipment (PPE) usually means a full face-shield, not just safety glasses. The fact is, an employee cannot be too careful with a machine that operates at several thousand RPM. Remember to document any safety requirements set forth by OSHA as that is the best evidence that safety procedures are being followed.
Grinder Safety – Ring-Testing
OSHA requires that grinding wheels be ring tested before mounting them. This simple step prevents the inadvertent mounting of a cracked grinding wheel. Ring-Testing involves suspending the grinding wheel by its center hole, then tapping the side of the wheel with a non-metallic object. This should produce a bell tone if the wheel is intact. A thud, or a cracked-plate sound, indicates a cracked wheel. For larger grinders, grinding wheels are laid flat on a vibration-table with sand evenly spread over the wheel. If the wheel is cracked, the sand moves away from the crack.
To prevent cracking a wheel during the mounting procedure, employees must be very carefully trained in those procedures. This starts with making sure the wheel is properly matched to that particular grinder, using proper blotters and spacers, and knowing exactly how much pressure to exert with a torque-wrench, just to mention a few things.
Grinder Safety – Wheel Covers
This OSHA-compliant Wheel-Cover allows no more than a total of 90 degrees of the wheel left exposed. (65 degrees from horizontal plane to the top of wheel-cover). Never exceed these wheel-cover maximum opening dimensions. Larger wheel-cover openings create a wider pattern of flying debris should the wheel explode.
A well-recognized safety precaution on bench/pedestal grinders is to stand well off to the side of the wheel for the first full minute before using the machine. Accidents have shown that grinding wheels are most likely to shatter/explode during that first minute. OSHA Instruction Standard #STD 1-12.8 October 30, 1978 addresses the conditional and temporary removal of the “Work Rest” for use only with larger piece parts based on the condition that “Side Guards” are provided.
Grinder Safety – Grinder Safety Do’s
- Always handle and store wheels in a careful manner
- Visually inspect all the wheels before mounting for possible damage
- Make sure operating speed of machine does not exceed speed marked on wheel, its blotter or container
- Check mounting flanges for equal size, relieved as required and correct diameter
- Use mounting blotters when supplied with wheels
- Be sure work rest is properly adjusted on bench pedestal and floor stand grinders
- Always use safety guard that covers a minimum of one-half the grinding wheel
- Allow newly mounted wheels to run at operating speed, with guard in place, for at least one minute before grinding
- Always wear safety glasses or some type of approved eye protection while grinding
- Turn off coolant before stopping wheel to avoid creating an out-of-balance condition
- Grind Don’ts
- Don’t use a wheel that has been dropped or appears to have been abused
- Don’t force a wheel onto a machine or alter the size of the mounting hole – If a wheel won’t fit the machine, get one that will
- Don’t ever exceed maximum operating speed established for the wheel
- Don’t use mounting flanges on which the bearing surfaces are not clean, flat And smooth
- Don’t tighten the mounting nut excessively
- Don’t grind on the side of conventional, straight or Type 1 wheels
- Don’t start the machine until the safety guard is properly and securely In place
- Don’t jam work into the wheel
- Don’t stand directly In front of a grinding wheel whenever a grinder is started
- Don’t grind material for which the wheel Is not designed
- Rockford Systems Can Help
- Rockford Systems offers a wide variety of safeguarding products for grinders.
Grinder Safety – Single-Phase Disconnect Switch and Magnetic Motor Starter
This single-phase unit is designed for motors that have built-in over-loads. Typical applications for these combinations include smaller crimping machines, grinders, drill presses, and all types of saws. The 115-V, 15-A disconnect switch and non-reversing magnetic motor starter are housed in a NEMA-12 enclosure. Enclosure size is It includes a self-latching red emergency-stop palm button and a green motor control start push button. It can be used on machines with 115-V and is rated up to 1/2 HP maximum. The disconnect switch has a rotary operating handle which is lockable in the off position only. This meets OSHA and ANSI standards. For machines with 230-V AC single-phase motors, a transformer is required to reduce the control circuit voltage to 115-V AC in order to comply with NFPA 79.
Grinder Safety – Double-Wheel and Single-Wheel Bench Grinder Shields
Double-wheel bench grinder shields provide protection for both wheels of the grinder with one continuous shield. The durable shield is made of clear, -inch-thick polycarbonate and measures 18-inch x 6-inch. A special shield bracket adds stability to the top of the shield. The single-wheel bench grinder shield is made of clear, -inch-thick polycarbonate and measures 6-inch x 6-inch. This sturdy, impact-resistant shield is designed for use when a single wheel needs safeguarding. These shields have a direct-mount base that attaches directly to the grinder table or pedestal.
PROTECTOR™ Series Shields
Rockford Systems redefines metalworking machine safeguarding with the launch of PROTECTOR™ Series Shields. These new patent-pending shields provide highest level of safety on market.
PROTECTOR Series Shields can include color-changing LED lighting nested into the frame of the shield to illuminate the work area during machine operation. The LED light strip is integrated into the shield frame and each strip packs 262 Lumens of light per linear foot. For example, the PROTECTOR 28” octagonal or circular shield provides 2180 Lumens, compared to a typical clip-on work lamp that provides only 800 Lumens. Operators will appreciate the non-reflective, true-color rendering white light illuminating their work area. When the shield is moved out of the safe work position, white LEDs switch off and red LEDs switch on, thereby providing visual indication that the shield is in the open position. All LED lighting has been manufactured to exacting IEC IP65 outdoor/wet location standards to withstand coolant and lubricant splashes.
PROTECTOR Series Shields can be upgraded with a safety-rated interlock switch or switches, dependent upon application. Interlocking shields exceed OSHA CFR 1910 regulations and ANSI B11 Series standards, and are considered a best safety practice.
Shield interlocks shut off or disengage power and prevent machine start-up when guard is not closed, thereby increasing operator safety and preventing bypassing. All safety interlock switches are mounted in a tamper-resistant NEMA 4 housing, comply with the IEC/EN 60947 safety standard and carry IEC IP66/67 device ratings. Additional motor starter or anti-restart devices may be required when incorporating interlocking devices into the Protector Series Shields in order to ensure safe and compliant operation.
PROTECTOR Series Shields are manufactured by Rockford Systems LLC in Rockford, Illinois, USA. All shields are shipped within 2-3 weeks.