What’s the Difference Between a Guard and a Shield

The terms guard and shield are often used interchangeably when referring to safeguarding cutting and turning machines. However, there is a significant difference between the two words.

Guards

OSHA 29 CFR 1910.217 defines a guard as an enclosure that prevents anyone from reaching over, under, around, or through the guard even if they really tried. Guards are often used when a machine risk assessment shows a high level of exposure to recognized hazards.

Guards can be separated into two categories: point-of-operation and perimeter. Point-of-operation guards are designed to enclose only the area on a machine where the work is actually done to make a finished part. A perimeter guard can be used when a larger area requires protection. Perimeter guards can also be used to enclose a group of machines that may not otherwise be safeguarded.

ANSI B11 safety standards require that guard access doors be electrically interlocked using switches designed to be difficult to defeat. This is particularly important for doors that are frequently accessed.

Shields

Shields, on the other hand, are designed for lower levels of exposures (to hazards). Most shields are designed to knock down chips and coolant in cutting/turning operations, while still providing visibility into the point of operation.

Other shields are designed to prevent inadvertent contact with rotating parts. A common example is the use of a chuck shield on an engine lathe. Although not required, shields may also be interlocked. Using an interlocked shield is considered best safety practices and is highly recommended when feasible.

When the question arises as to which to apply, remember that guards must always provide a higher level of protection than shields.

Rockford Systems encourages all employees to exceed the minimum requirements and abide by best safety practices at all times.

Basic Requirements for a Point-of-Operation Guard

OSHA’s Code of Federal Regulations 1910.212 General Requirements For All Machines states that “Point of operation is the area of a machine where work is actually performed upon the material being processed. The point of operation of machines whose operation exposes an employee to injury, shall be guarded.”

There are five basic requirements to consider (OSHA and ANSI) when choosing a point-of-operation guard. They are:

  1. hands/fingers can’t reach through, over, under, or around
  2. meets OSHA’s Table O-10 for openings and distances
  3. does not create secondary hazards between guard and machine parts
  4. offers good visibility (for the operator) when required
  5. uses fasteners not readily removable (requires a tool to remove/adjust)

Two additional considerations (from ANSI B11.1-2009) for best safety practices include:

  • materials strong enough to protect the operator and others
  • constructed of material free of sharp edges

Rockford Systems encourages all employees to exceed the minimum requirements and abide by best safety practices at all times.

Safeguarding Choices for Milling Machines (With or Without Automatic Control)

OSHA’s Code of Federal Regulations 1910.212 General Requirements For All Machines specifies that one or more methods of machine guarding shall be provided to protect the operator and other employees in the machine area from hazards such as those created by point of operation, ingoing nip points, rotating parts, flying chips, and sparks.

Choices for these safeguarding methods may include one or more of the following:

  • chip and coolant shields
  • guards (fixed, movable, and/or interlocked)
  • presence-sensing devices
  • two-hand control
  • awareness barriers and devices

Correctly applied chip/coolant shields meet OSHA’s minimum requirements for point-of-operation protection for operators of manually operated milling machines.

Automated (CNC) mills—machining centers— require interlocked guards at the point of operation.

Rockford Systems encourages all employers to exceed minimum requirements and abide by the best safety practices found in ANSI B11.8-2011 (R2008) for drilling, milling, and boring machines, and ANSI B11.23-2002 (R2007) for machining centers. The key to employee safety is to observe best safety practices at all times.

OSHA Inspection Priorities

The following is an excerpt taken from OSHA Fact Sheet DEP FS-3783.

OSHA inspectors are experienced, well-trained industrial hygienists and safety professionals whose goal is to assure compliance with OSHA requirements and help employers and workers reduce on-the-job hazards and prevent injuries, illnesses, and deaths in the workplace. Since OSHA cannot inspect all 7 million workplaces it covers each year, the agency focuses its inspection resources on the most hazardous workplaces in the following order of priority:

1. Imminent danger situations—hazards that could cause death or serious physical harm receive top priority. Compliance officers will ask employers to correct these hazards immediately or remove endangered employees.

2. Severe injuries and illnesses—employers must report:

  • All work-related fatalities within 8 hours.
  • All work-related inpatient hospitalizations, amputations, or losses of an eye within 24 hours.

3. Worker complaints—allegations of hazards or violations also receive a high priority. Employees may request anonymity when they file complaints.

4. Referrals of hazards from other federal, state or local agencies, individuals, organizations or the media receive consideration for inspection.

5. Targeted inspections—inspections aimed at specific high-hazard industries or individual workplaces that have experienced high rates of injuries and illnesses also receive priority.

6. Follow-up inspections—checks for abatement of violations cited during previous inspections are also conducted by the agency in certain circumstances.

Normally, OSHA conducts inspections without advance notice. Employers have the right to require compliance officers to obtain an inspection warrant before entering the worksite.

Click here for a full PDF version of OSHA Fact Sheet DEP FS-3783.

Most Common Reasons To Upgrade Machine Safeguarding

Hydraulic press with a light curtain and two-hand control device as the point-of-operation safeguard. Also has a hydraulic control with control reliability.
Hydraulic press with a light curtain and two-hand control device as the point-of-operation safeguard. Also has a hydraulic control with control reliability.

People often wonder what motivates companies to make improvements in their machine safeguarding. As a supplier of this equipment, we often find that four things influence these decisions.

First, serious accidents are sometimes the reason. Unfortunately, machine safeguarding may be a back burner issue until something catastrophic occurs.

Second, inspections by insurance companies who write worker’s compensation policies often uncover issues involving unguarded machines. This prompts them to throw a company into the insurance “pool” for high risk accounts resulting in higher premiums.

Third, state or federal OSHA inspections may reveal similar problems with incomplete machine guarding, resulting in fines, along with the costs of abatements/corrections.

Fourth, some larger companies invoke their own machine safeguarding rules that go “above and beyond” OSHA regulations and ANSI safety standards.

In any case, Rockford Systems, LLC offers machine safety surveys where one of our machine safety specialists will visit your plant to conduct a detailed inspection of either specific machines in question, or of all your machines if you wish.

Safeguarding Choices For Metal Cutting Saws 

Although OSHA’s Code of Federal Regulations does not have a machine specific regulation for metal cutting saws, 1910.212 General Requirements For All Machines says that one or more methods of machine guarding shall be provided to protect the operator and other employees in the machine area from hazards such as those created by point of operation, ingoing nip points, rotating parts, flying chips and sparks.
 
Choices for these safeguarding methods may include one or more of the following:

  • blade guards (fixed, movable, and/or interlocked)
  • polycarbonate shields (for chip/coolant control)
  • two-hand control (for parts that can be fixtured)
  • awareness barriers and devices (to prevent unauthorized people from being in the hazard area)

Although presence-sensing devices are also listed as a possible means of safeguarding, their practical application is often very limited.
 
Other point-of-operation safeguarding may include point-of-operation devices (two-hand control and/or push sticks) and safe holding (based on the size and shape of the part).
 
A correctly applied polycarbonate shield meets OSHA’s minimum requirement for preventing chips and coolant from striking the operator or from collecting on the floor where they might present a slip/trip hazard. Recent safety standards, however, contain new warnings regarding the lifespan of polycarbonate. The impact protection of this material may only be 2-3 years when exposed to cutting fluids on a regular basis. It is a good idea to keep replacement polycarbonate shields on hand. 
 
ANSI B11.10 clause 8 on point-of-operation safeguarding requires a safety (blade) guard to protect the operator from an exposed portion of the saw blade. Because it’s a primary requirement, safety (blade) guards have been provided on most saws by machine OEMs since the inception of OSHA in the early 1970s.

Do I Really Need to Safeguard My Machines?

Unguarded Lathe

Yes, you really do need to safeguard machines in your workplace. But to what extent can be a matter of interpretation based on minimum safety requirements (OSHA regulations), or best safety practices (ANSI standards).

Most employers are familiar with OSHA (Occupational Safety & Health Administration) and the enabled OSH Act of 1970. Under the OSH Act, employers are responsible for providing a safe and healthful workplace. Employers must comply with all applicable OSHA standards. Employers must also comply with the General Duty Clause of the OSH Act, which requires employers to keep their workplace free of serious recognized hazards.

By law, employers are legally required to follow OSHA regulations. That means an OSHA inspector will issue citations for noncompliance to their CFR (Code of Federal Regulations). OSHA’s CFR SubPart O—Machinery and Machine Guarding has six (6) machine specific safeguarding regulations which are:

1910.213 Woodworking Machinery
1910.214 Cooperage Machinery

1910.215 Abrasive Wheel Machinery
1910.216 Mills and Calendars
1910.217 Mechanical Power Presses

1910.218 Forging Machines

safeguarded lathe

OSHA regulations for safeguarding most other machines falls under 1910.212 General Requirements For All Machines which specifies that the operator and others in the machine area be protected from exposure to hazards.

However, ANSI’s B11-Series Safety Standards (which has 24 machine categories) are often used to fill in the details for specific safeguarding and can be used as reference material by OSHA inspectors. Even though ANSI safety standards are voluntary, they could become legally mandatory if an OSHA citation mentions specific ANSI standard for you to comply to.

The bottom line is that all employers should strive to exceed minimum requirements and abide by the best safety practices found in the ANSI B11 standards. The key to employee safety is to observe best safety practices at all times. After all, it could be a matter of life and death!