Demystifying Die Safety Blocks


Picture13Die safety blocks are called by many names: safety blocks, ram blocks, die blocks or prop blocks. Regardless of the term, die safety blocks all have the same purpose: provide protection to anyone working in the die area from a free-falling upper die/slide. This all-too-common accident happens in the event of a brake or counterbalance failure, broken pitman or adjusting screw, or a sudden loss of hydraulic pressure on presses.  While die safety blocks are on the surface simple devices, there are many factors to consider in choosing what type of to use, as well as how many to use or where to put them. As a result many organizations struggle with this topic.


Die safety blocks are required by OSHA CFR 29, Subpart O, 1910.217 (d)(9)(iv) Mechanical Power Presses which states, “The employer shall provide and enforce the use of safety blocks for use whenever dies are being adjusted or repaired in the press.” OSHA does not require the use of safety blocks during die setting; however, companies may include them during die setting procedures as a best safety practice. Proper use of die safety blocks also satisfies OSHA’s lockout/tagout requirements for controlling mechanical energy.

047Anytime an employee needs to put their hands in the die area of a press or is required to work on the die, they must follow OSHA regulations without exception. At no time should the employee make any adjustments or service within the die space area without taking proper protection measures that meet OSHA and ANSI requirements. Regardless of how time-consuming, the company is responsible—and liable—for these procedures in a press shop.

With the press motor off and the flywheel at rest (for mechanical presses), safety blocks are placed between the die punch and holder with the machine stroke up.  The number of safety blocks is determined by the size of the press bed and the weight the blocks must support. On larger presses, the total slide weight must then be distributed among the quantity of safety blocks required.  In some applications, as many as four safety blocks may be required.

The ram is usually adjustable; therefore, wedges or the adjustable screw device is offered to provide a proper fit. If the die takes up most of the space on the die set, it may be difficult to find a place to insert the block. To avoid accidentally stroking the press or leaving the safety block in the die after use, an electrical power cut-off interlock system should be used.

According to ANSI B11.19-2003, safety blocks “shall be interlocked with the machine to prevent actuation of hazardous motion of the machine.” The electrical interlock system for die safety blocks must be interfaced into the control system so that when the plug is pulled, the power to the main drive motor and control is disconnected. If the machine has a mechanical energy source, such as a flywheel, it must come to rest before the die block can be inserted.


Three factors need to be determined to guide your selection of safety blocks:  static load, block length and block size.

  1. Determine Static Load

The actual static load that the die safety block(s) will support is determined by adding the actual weights of the press slide and slide components (ram-adjustment assembly, connection rod[s] or pitman arm[s], and the upper die).

If this weight cannot be determined, an approximate static load can be calculated using the formula below. Allow 2000 pounds of static load for each cubic foot displaced in the press bed area (front to back x right to left) multiplied by the shut height (die space) of the press. Note: When using this formula, the calculated approximated static load has a safety factor of two (2).

NEW Sfty Blk Shut Hght-01

Allow 2000 pounds of static load for each cubic foot displaced in the press bed area (front to back x right to left) multiplied by the shut height (die space) of the press.  Note:  When using this formula, the calculated approximated static load has a safety factor of two (2).

Static Load Formula:

  • (Press Bed Area (sq in) x Shut Height (in))/(Cubic Inches/Cubic Feet (1728 cu in/cu ft constant))
  • Cubic feet displaced x 2000 lb/cubic foot = Total Static Load


  • Press Bed Area = 48 in x 96 in
  • Shut Height = 24 in
  • (48 x 96 x 24)/1728 or 110,592/1728 = 64 cu ft
  • 64 cubic feet displaced x 2000 lb/cu ft = 128,000 Total Cubic Static Load
  1. Determine Block Length

With the machine at the top of its stroke; stroke up—adjustment up (S.U.A.U.), measure the space between the upper and lower die set plates (not the distance between the bolster and slide). This gives the maximum safety block length.

To determine the stroke up—adjustment down (S.U.A.D.) measurement, subtract the ram adjustment from the S.U.A.U. figure. This provides the minimum length of the die safety block.

Total Length of Die Safety Block Required ___________”


  1. If wedges will be used, subtract 11 ⁄2″ maximum. This is an allowance for variation in the stopping point of the crankshaft or adjustment of the ram.

Total Length of Die Safety Block Required ____________”

  1. When an adjustable screw is added to an octagonal safety block, the minimum length of the aluminum portion of the safety block is as follows:

When an adjustable screw device is added to an octagonal safety block and the screw is all the way inside of the safety block, it will add 2″ to the overall length of small and medium safety blocks and 21 ⁄2″ to the overall length of large safety blocks. Therefore, subtract 2″ for small or medium blocks and 21 ⁄2″ for large blocks to determine the length of the aluminum portion of the die block.


  • If the minimum overall length of the small or medium safety block required is 101 ⁄2″ with any size adjustable screw device, the aluminum portion of the safety block would be 81 ⁄2″ (101 ⁄2″ – 2″ = 81 ⁄2″).


  • If the minimum overall length of the large safety block required is 16″ with any size adjustable screw device, the aluminum portion of the safety block would be 131 ⁄2″ (16″ – 21 ⁄2″ = 131 ⁄2″).

Total Length of the Aluminum Portion of the Die Safety Block ___________”

  1. Determine Block Size

The size of the die safety block (small, medium, large) is determined by one or both of the following factors:

  1. The size of the block itself and the area available in the die.
  2. The static load capacity of the block (small, medium, large) versus the total static load being supported.


Wedge Safety Blocks

Rockford Systems offers a variety of die safety blocks, electrical interlock systems, accessories and operator safety resources.  Our line of high-strength, aluminum wedge die safety blocks that are lightweight and come in several shapes (x-shape, u-shape, octagon shape) and sizes (small, medium, large) to meet every press application. The unique shape and mechanical properties of the 6063-T5 aluminum have been calculated according to stringent structural aluminum design analysis standards to provide high strength.  Blocks are sold in standard 9′ lengths or can be cut to any size.

Rockford Systems also offers adjustable die safety blocks.  These adjustable die safety blocks feature a tough malleable-iron bell-bottom base. The blocks also have a convenient handle for lifting and precision-cut acme threads for easy adjustment and extra rigidity.  The adjusting screw can be easily adjusted up or down by hand. Turning holes are also provided in the screw neck to faciliDie Block-Octagon Static Loadtate the use of a turning bar, if required.

All Rockford Systems static load charts (see example at right) are found on on die block product pages.

Die Block Electrical Interlock System
Die Block Electrical Interlock System

Unlike most competitors, Rockford Systems offers electrically interlocked systems.  The interlock system is available in a yellow plug with one contact (KTS518) or an orange plug with two contacts (KTS533). The electrical interlock system for die safety blocks includes the plug, a 24-inch long chain, a receptacle, and an electrical mounting box.

Additional die block accessories available from Rockford Systems include lifting handles, holders and bases.  Our octagon shape safety block comes with an optional heavy-duty steel, adjustable screw device to prevent any space between the block and die when various dies are used or when the slide is adjusted.

Danger Sign for Die Safety Blocks
Don’t forget to post the appropriate danger signs near all machinery in the plant. The purpose of danger signs is to warn personnel of the danger of bodily injury or death. The suggested procedure for mounting this sign is as follows:
1) Sign must be clearly visible to the operator and other personnel
2) Sign must be at or near eye level
3) Sign must be PERMANENTLY fastened with bolts or rivets

Click HERE to watch the Die Safety Block Video Demonstration.

Please call 1-800-922-7533 or visit for more information.


Playing It Safe With Robotics


Robotics is a growing field as more and more companies are incorporating industrial automation into their production processes. In just the first nine months of 2016, 23,985 robots were ordered from North American companies, many of which require machine guarding equipment to maximize productivity and safety. Robots are used for replacing humans who were performing unsafe, hazardous, highly repetitive, and unpleasant tasks. They are utilized to accomplish many different types of application functions such as material handling, assembly, arc welding, resistance welding, machine tool load/unload functions, painting/spraying, etc.

Studies indicate that many robot injuries occurring in robotic automation typically occur during non-routine operating conditions, such as programming, maintenance, repair, testing, setup, or adjustment when the worker may temporarily be within the robot’s working envelope.

Non-Safeguarded Robots
Non-Safeguarded Robots

As stated by OSHA, mechanical hazards might include workers colliding with equipment, being crushed, or trapped by equipment, or being injured by falling equipment components. For example, a worker could collide with the robot’s arm or peripheral equipment as a result of unpredictable movements, component malfunctions, or random program changes. The worker could be injured by being trapped between the robot’s arm and other peripheral equipment or being crushed by peripheral equipment as a result of being impacted by the robot into this equipment.

Mechanical hazards also can result from the mechanical failure of components associated with the robot or its power source, drive components, tooling or end-effector, and/or peripheral equipment. The failure of gripper mechanisms with resultant release of parts, or the failure of end-effector power tools such as grinding wheels, buffing wheels, deburring tools, power screwdrivers, and nut runners are a few of the possibilities.

Non-Safeguarded Robot
Non-Safeguarded Robot

Human errors can result in hazards both to personnel and equipment. Errors in programming, interfacing peripheral equipment, connecting input/output sensors, can all result in unpredictable movement or action by the robot which can result in personnel injury or equipment breakage.

Human errors in judgment frequently result from incorrectly activating the teach pendant or control panel. The greatest human judgment error results from becoming so familiar with the robot’s redundant motions that personnel are too trusting in assuming the nature of these motions and place themselves in hazardous positions while programming or performing maintenance within the robot’s work envelope.


Robots in the workplace are generally associated with the machine tools or process equipment. Robots are machines, and as such, must be safeguarded in ways similar to those presented for any hazardous remotely controlled machine, falling under the general duty clause or OSHA 1910.212(a)(1) or 1910.212(a)(3)ii.  Refer to and OSHA’s compliance directive on robotics STD 01-12-002 at for more information.

Robotics Packaging Cell Courtesy: Banner Engineering
Robotics Packaging Cell
Courtesy: Banner Engineering

Various techniques are available to prevent employee exposure to the hazards which can be imposed by robots. The most common technique is through the installation of perimeter guarding with interlocked gates. A critical parameter relates to the manner in which the interlocks function. Of major concern is whether the computer program, control circuit, or the primary power circuit, is interrupted when an interlock is activated. The various industry standards should be investigated for guidance; however, it is generally accepted that the primary motor power to the robot should be interrupted by the interlock.

Although ANSI standards are guidelines, many U.S. industry experts experts agree that ANSI standards provide the best guidelines for safeguarding machinery that doesn’t have a vertical OSHA requirement.
ANSI/RIA R15.06-2012 is the most recent U.S. Standard on Industrial Robots, which requires that perimeter guards contain the robot automation. These guards are required to have a 12-inch sweep and a 60-inch height (ANSI/RIA R15.06-1999). However, CSA 2003 cite best practices at a 6-inch (.15m) sweep and a 72-inch (1.8m) height.

When a robot is to be used in a workplace, the employer should accomplish a comprehensive operational safety/health hazard analysis and then devise and implement an effective safeguarding system which is fully responsive to the situation. In general, the scale of the automation cell will drive the scale of the safeguarding. (Various effective safeguarding techniques are described in ANSI B11.19-2010.)

During Rockford Systems Onsite Risk Assessments and Onsite Machine Surveys, we find one of the most common problems with robotics is the failure to accurately calculate safety distances, typically used in regard to the installation of safety mats. Robots make rapid and wide-reaching moves. The goal is to stop a robot before it can hurt someone.

Robotics Palletizer and Stretch Wrapper Cell Courtesy: Banner Engineering
Robotics Palletizer and Stretch Wrapper Cell
Courtesy: Banner Engineering

Any robot that moves more that 10 inches per second must be safeguarded adequately. Safe distance is determined by the following Robotics Industry Associations (RIA) formula with the following parameters:

DS= 63 inches per second (IPS) X(TS+ TC+ TR) + DPF
DPF= 1.2 m (48 in.)

DS= minimum safe distance
TS= stopping time of device
TC= worst stopping time of control system
TR= response time of safeguarding device including interface
DPF= maximum travel distance toward a hazard once someone has entered the field


So the total horizontal space to be protected is 48 in. plus 63 IPS, multiplied by the total time delay between detection of a person in the protected area and the actual time it takes for the robot to stop.

It’s imperative that the automation cell and all aspects of machine use be identified and considered when selecting and implementing a robotics safeguarding. Ultimately, the best type of protective measure will be the device or system that provides maximum protection, with minimal impact on normal machine operation.

Please call 1-800-922-7533 or visit for more information.

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.


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, 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.

PROTECTOR Series Shields
PROTECTOR Series Shields
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!