Shield Against Debris

When a machinist is cutting, drilling, shaping or milling raw materials, there are always inherent risks. Thankfully, proper and up-to-date safeguarding equipment drastically minimizes the risks that machines pose. In this article, we look at one of the most basic and most critical components in machine safeguarding: the safety shield.

Before we start, we need to clarify the terms “guard” and “shield.” These are often used interchangeably when referring to safeguarding equipment, yet the two categories are very different. OSHA 29 CFR 1910.217 defines a guard as an enclosure that prevents anyone from reaching over, under, around, or through to a hazard.

Guards are used when a machine risk assessment shows a high level of exposure to recognized hazards. Shields, on the other hand, are designed for lower levels of exposures to hazards, while providing visibility into the point of operation. Shields typically have a transparent plastic panel with rugged framing, while a guard is solid metal, although it should be noted that not (not all shields have a framework, and that many industrial guards use aluminum for framework.).

Flying debris protection
The purpose of safety shields is to protect the machinist and bystanders from moving parts, flying debris, coolant, sparks, and other potential safety hazards by enclosing the danger (shields don’t enclose a hazard, they providing a barrier between plant personnel and the hazard) behind a rugged, impact-resistant panel. Shields attach to machinery, either temporally or permanently, fitting over blades, drills, lathe chucks, grinding wheels and other dangerous components (blades, cutting tools, chucks, grinding stones and other hazardous rotating components.).

Perhaps the greatest danger shields protect against is flying debris, an all-too-common occurrence in machine shops with the potential to bring about serious injury to an operator’s eyes, face, or body. The costs of a flying debris injury can add up quickly. Costs may include workers’ compensation claims, medical expenses, lost production time, and the possibility of permanent scarring and blindness.

For instance, consider an abrasive wheel grinder. Grinders are one of the most common pieces of machinery in maintenance shops, wheel grinders are powerful and designed to operate at high speeds. Depending on the equipment, the wheels can revolve at an incredible 10,000 surface feet per minute, and can loosen sharp chips or particles that can fly into an operator’s eyes or face. If a grinding wheel shatters while in use, the fragments can travel at more than 300 miles per hour directly at the operator, more than fast enough to penetrate the skull and cause traumatic brain injury. In situations like this a safety shield is the last line of defense against tragedy. (Our shields do NOT provide protection from catastrophic machine failure, which I would consider an exploding grinding stone) Even if the operator is wearing proper personal protective equipment, flying chips can cause life-threatening injuries without a shield installed. A shield can make the difference between a day that ends successfully and a day one that ends in the hospital.

Safety standards
Given their critical importance to operator safety, it is not surprising that ANSI, OSHA and other standards governing machine safeguarding heavily rely upon shields. Specific requirements largely depend on the type of machinery being safeguarded. Before installing a new shield on any machine the safety manager must ensure that the shield conforms to the appropriate, up-to-date standard for that machine.

Besides grinders, shields are typically installed on drilling machines, lathes, milling machines, band saws (saws), belt sanders, and disc sanders (sanding machines), and boring machines.. TheseThe seven (eight) machines represent over 95 percent of all shielding applications. Different standards outline the type of shield design and size that is allowed on each. In some cases, more than one type of shield per machine may be necessary to provide protection.

Types of shields
Shields come in dozens of designs, sizes and shapes. In their most basic form they can be broken out into fixed, portable, adjustable and interlocked categories, or a mixture of these features.

Fixed/portable
The most obvious characteristic of a fixed shield is that it is a permanent part of the machine. Tools are needed for its removal making it difficult to bypass. It is also not dependent upon other moving parts to perform its intended function, further increasing the protection. In contrast, a portable shield can be removed from the machine when not in use. Often, smaller shields will feature a pull magnetic base that attaches to a flat surface on the machine being safeguarded. Being removable, portable shields can be set aside for maintenance or moved to a similar machine. There are also large freestanding portable shields used to protect the area between machines, along aisles, or the backside of a machine.

Adjustable
An adjustable shield can be positioned for maximum protection during operation and swung out of the way for easy access to the workpiece and tooling. Types of adjustable shields are those mounted on brackets that allow for slide adjustments to fit workpieces; on steel ball-and-socket arms for simple movements and adjustments; or on flexible spring-steel arms offering virtually unlimited adjustment possibilities and long-term holding power.

Interlocked
Although not required, (I don’t like saying “not required” fiIt is best practices that sshields featuring movable parts that can be opened without using tools should be interlocked with the machine control system. The interlock prevents machines from starting until the shield is positioned safely in front of the hazardous area. Additionally, if the shield is moved away from the hazardous area while the machine is running, the interlock will send a stop signal to turn the machine off.

This way the hazards covered by the shields will be effectively controlled if the shield is opened and the hazard is exposed. (Explain differently, this is confusing. Hazardous machine movement is prevented when the shield is opened) When an interlocked shield is opened or closed, a tripping mechanism automatically shuts off the power to disengage operations. The machine cannot cycle or be started until the shield is back in place. (Maybe wrap all three previous sentences into one statement. Sounds odd and non-technical)

Modern machines rely on electrical interlocks since they are already fitted with an electrical control system. The interlock is connected to the safety circuit of the machine and will prevent machine start-ups when the shield is swung open, even if the power switch is “ON”. It is only after the shield is closed that the machine can be restarted and normal operation resumed. Switches and sensors connected to these systems can be something as simple as a micro-switch or a reed switch, or as complex as a non-contact sensor with an electromagnetic locking device. Non-contact interlocking devices available today use coded RF signals or RF ID technologies to ensure that the interlock cannot be defeated by simple measures, like taping a magnet to a rA safety relay will monitor the interlock switch for failure, providing a notification if the interlock has been removed or is not functioning correctly.

Impact resistance
It goes without saying that Aa transparent shield needs to be highly impact resistant, along with providing an unobstructed and undistorted view. Impact resistance of a material can be measured in different ways, and the test method varies depending on the material being evaluated. In the United States, the notched Izod impact resistance test, as outlined in ASTM D256, is a common method of measuring the toughness of a plastic material.

It is important to note that increasing the thickness of a shield beyond a certain level does not always improve or increase impact resistance. A shield made of tougher material can be down-gauged to be thinner — and, therefore, more cost-effective — than one made from a more brittle material while still offering the same or superior level of protection for operators. Not sure the impact resistance data belongs in this article.

Innovations
Having lain dormant for decades, innovation has finally come to the safety shield business. Companies are bringing new materials and features to the product category that are enhancing operator safety yet making it less expensive for machine shops to be fully compliant with regulations.

An example of this new problem-solving advancement is the incorporation of bright LED lighting into the shield frame to yield higher visibility of the work area. Operators have often complained that shields limit visibility because of reflectivity or obstruction. Unlike an incandescent, LED lighting is not-reflective, cool and renders true colors. Besides the white lighting illuminating the work area while in operational mode, different LED colors can be programmed to act as visual indicators.

For example, when the shield is moved out of the safe work position, the white LED can switch off automatically and red LED can switch on to warn the operator. If you plan to purchase a shield with an LED be aware that the lighting must be manufactured to exacting IEC IP65 outdoor/wet locations standards to withstand splashes of coolant and lubricant from the machine.

Another innovation is modularity. Different machines require different shields, and one size rarely fits all. Shield manufacturers have embraced the modular design concept so that shield shape, size, mount, arm, offset, lighting, interlocking and safety monitoring can be configured to engineer the best solution for even the most unique challenge.. Available today are various mounting options, including opposite-hand mounting scenarios for left-handed operators. Left handed or not, handles for drills, mills, boring machines, etc are located on the right side of most machines. Opposite side mounting locations are selected based on available machine frame surface and/or other obstructions on a machine. Shields are vertically and horizontally adjustable to clear varying work setups and table heights.

Finally, there is the issue of operators bypassing shields, either by pushing them out of the way or tampering with the equipment.

Tamper-resistant interlock enclosures (switches) and redundant safety monitoring (monitoring does nothing for preventing tampering) go a long way towards stopping bypassing. However, a quality shield that doesn’t interfere with operation of a machine is a better answer. A shield defeats its purpose if it impedes a worker from performing a job quickly and comfortably. When properly installed and designed for a specific machine, a shield will actually enhance efficiency because it will relieve apprehensions about an injury.

Learn about Rockford Systems’ line of PROTECTOR Series Shields offering the highest level of safety on the market.

Lack of Machine Guarding Again Named to OSHA’S Top 10 Most Cited Violations List

Every year around this time, the awards season kicks off with the Emmys, Golden Globes and the grand daddy of them all, the Oscars, eagerly announcing their lists of nominations. At the same time — and on a far more somber note — another roll call is issued, this one from the Occupational Safety & Health Administration (OSHA). Unlike Hollywood’s awards celebrations, however, no one wants to be nominated for OSHA’s Top Ten Most Cited Violations list, let alone take home the top prize.

OSHA revealed its 2017 Top 10 list at the National Safety Congress & Expo in the Indiana Convention Center. The top ten are:

1. Fall Protection – (1926.501): 6,072 violations
2. Hazard Communication (1910.1200): 4,176 violations
3. Scaffolding (1926.451): 3,288 violations
4. Respiratory Protection (1910.134): 3,097 violations
5. Lockout/Tagout (1910.147): 2,877 violations
6. Ladders (1926.1053): 2,241 violations
7. Powered Industrial Trucks (1910.178): 2,162 violations
8. Machine Guarding (1910.212): 1,933 violations
9. Fall Protection – Training Requirements: 1,523 violations
10. Electrical – Wiring Methods (1910.305): 1,405 violations

While reviewing the list, it is important to remain aware that the Federal Occupational Safety & Health Administration (OSHA) is a small agency. When tallied up to include its state partners, OSHA only has 2,100 inspectors who responsible for the health and safety of 130 million American workers, employed at more than 8 million work sites. This translates to about one compliance officer for every 59,000 workers. As a result, some serious injuries are not reported and thousands of potential violations go without citation or fines. In fact, numerous studies have shown that government counts of occupational injury are underestimated by as much as 50 percent. Employers are required to record all injuries meeting the OSHA’s ‘recordable injury’ criteria (except minor first-aid cases) on the OSHA 300 Log, and those meeting the ‘reportable’ criteria (e.g., hospitalizations or deaths), are to be reported to OSHA immediately, or within 24 hours of occurrence, as per the criteria defined in 29 CFR 1904. But it doesn’t mean all of them do.

MACHINE (UN)SAFEGUARDING IN TOP 10 MOST CITED VIOLATIONS
The absence of required machine safeguarding remains a perennial member of OSHA’s Top 10 Most Cited Violations, and 2017 was no exception. It was named number eight on the list with a total of 1,933 violations. These violations refer to OSHA 1910.212 for failing to have machines and equipment adequately guarded. Any machine part, function, or process that might cause injury should be safeguarded. When the operation of a machine may result in a contact injury to the operator or others in the area, the hazard should be removed or controlled.

A lack of machine safeguarding also held the dubious distinction of making the list of OSHA’s ten largest monetary penalties for the year — not once but four times. In fact, the largest proposed monetary penalty, a staggering $2.6 million (USD), arose from an incident where a worker was crushed to death while clearing a sensor fault in a robotic conveyor belt. OSHA alleges that the company failed to use energy control procedures to prevent robotic machinery from starting during maintenance. The manufacturer also was cited for exposing employees to crushing and amputation hazards as a result of improper machine guarding, plus failing to provide safety locks to isolate hazardous energy.

Despite these headline fines, the repercussions for employers putting workers in harm’s way remain small under the 1970 Occupational Safety and Health Act. The average federal fine for a serious workplace safety violation was $2,402 in fiscal year 2016, according to the most recent report by the AFL-CIO. And the median penalty for killing a worker was $6,500.

According to the most recent Bureau of Labor Statistics data, manufacturing plants reported approximately 2,000 accidents that led to workers suffering crushed fingers or hands, or had a limb amputated in machine-related accidents. The rate of amputations in manufacturing was more than twice as much (1.7 per 10,000 full-time employees) as that of all private industry (0.7). The bulk of these accidents occurred while removing jammed objects from a machine, cleaning or repairing the machine, or performing basic maintenance. These injuries were all largely preventable by following basic machine safeguarding precautions. Rockford Systems is committed to helping organizations reduce injuries and fatalities due to a lack of or non-compliant machine safeguarding. By creating a culture of safety in the workplace, Rockford Systems can help plant managers significantly reduce the number of on-the-job injuries and fatalities that occur annually, plus guard against hefty fines, lost production and increased insurance premiums.

Which leads to the question… “Where do we begin?”

TRAINING AND EDUCATION

Ignorantia juris non excusat (“ignorance of the law excuses not”). Recognizing that education is key to safety, Rockford Systems has offered its Machine Safeguarding Seminars for more than two decades. Thousands of safety professionals have attended the seminars from industries as diverse as aerospace and metal fabrication, to government and insurance.

Held ten times a year at our Rockford, Illinois headquarters, the 2.5 day seminars address key topics in safeguarding with a focus on OSHA 29 CFR and ANSI B-11 standards as they relate to specific machine applications and production requirements. Safeguarding equipment, both old and new, is not only explained in depth in the classroom, but demonstrated under power on the shop floor. Most of these machines are equipped with more than one type of safeguarding product so that attendees can see how different guards and devices can be applied.

Roger Harrison, Director of Training for Rockford Systems and an industrial safeguarding expert with over 25,000 hours of training experience, conducts the Machine Safeguarding Seminar.

>Another valuable educational resource is OSHA-10 General Industry and OSHA-30 General Industry training courses, both of which cover machine guarding. All of our training can be provided at your site, if preferred. To learn more about the Rockford Systems training curriculum, please visit https://www.rockfordsystems.com/seminars/

Rockford Systems also provides a variety of FREE machine safeguarding resources for your organization. Please visit our RESOURCES page to find videos, blogs, quick reference sheets, and more or visit our YouTube channel to download past webinar recordings.

ASSESSMENTS
If your organization is interested in safeguarding solutions, consider a Machine Risk Assessment or Machine Safeguarding Assessment as the critical first step in any machine guarding process as outlined in ANSI B11. Most assessments, but not all, follow the basic steps outlined below.

Step 1 – Provide Machine List
To get started, please provide Rockford Systems a list of all machines (manufacturer, model number, and machine description of each machine) to be assessed. This machine list is needed to determine the estimated resource requirement for the onsite audit. Upon receipt of your machine list, an Assessment Proposal will be provided, generally within 24 hours of receipt. Please email your machine list and any machine photos (optional) to sheryl.broers@rockfordsystems.com.

Step 2 – Schedule Onsite Visit
During the assessment, a machine safeguarding specialist will visit your site and conduct a complete audit of all machines identified on the list and evaluate their compliance in five guarding areas (Safeguards, Controls, Disconnects, Starters, and Covers). The assessment is based on OSHA 1910.212 General Requirements (a)(1), ANSI B11 Safety Standards for Metalworking, ANSI/RIA R15.06-2012 Safety Standards for Industrial Robots, and NFPA 79. If Rockford Systems, LLC has additional specific safeguarding requirements above and beyond OSHA 1910.212 and ANSI B11, please provide them before the site visit and we will incorporate them into the assessment.

Also, during the assessment, we may request copies of electrical, pneumatic and/or hydraulic schematics and operator manuals for specific machines. This information is needed for our Engineering Department to review the control circuit for electrical compatibility of equipment being offered, to verify control reliability of the control circuit, to determine interfacing requirements of suggested equipment. If requested, this information would be needed before advancing to Step 3 below.

Step 3 – Receive Compliance Report and Safeguarding Project Proposal
Upon completion of the assessment, a Compliance Report and Safeguarding Project Proposal will be provided to that identifies where each machine is in, or not in, compliance with the above stated regulations and standards. Where not in compliance, we will suggest guarding solutions to bring the machines into compliance, along with associated costs and timeframes.

We look forward to assisting your organization with its safeguarding needs. A team member will call you within 24 hours to further discuss your needs and applications. We are here to help businesses large and small address machine safety challenges and to remove the burden of managing the growing legal complexity of OSHA, ANSI and NFPA requirements from simple turnkey solutions to build-to-spec customized solutions.

Please contact sheryl.broers@rockfordsystems.com or call 1-815-874-3648 (direct) to get started on an assessment today.

PRODUCTS
If you are looking for Machine Safeguarding Products, please visit our PRODUCTS page that offers over 10,000 safeguarding solutions for drill presses, grinders, lathes, milling machines, press brakes, power presses, radial arm drills, riveters and welders, robots, sanders, saws and more.

RETURN ON INVESTMENT
Not sure if the investment in machine safeguarding provides a return on the investment (ROI), it absolutely does and we can help you calculate it. Please read our detailed blog post on this topic.

For more information on how avoid machine injuries and fatalities, please visit www.rockfordsystems.com.

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.