DIE SAFETY BLOCKS
Safety Blocks with adjustable screw are quick and easily adaptable
Safety Blocks provide safety during set up and maintenance for power presses. This is done by mechanically and electrically preventing inadvertent die closure.
The new 3” round Safety Blocks are for smaller presses, with a maximum static load of 35 tons and having a wide span of adjustable heights. Blocks are made of high strength light weight extruded aluminum.
The standard horseshoe shaped die blocks can be used in large presses, with a maximum static load of 125 tons. Proper selection of style and size are determined by the press’ static load and required range of open height.
Die safety blocks are required by OSHA, and in CFR 29, Subpart O, 1910.217 (d)(9)(iv) Mechanical Power Presses, states, “The employer shall provide and enforce the use of safety blocks for use whenever dies are being adjusted or repaired in the press.”
Anytime 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 employer is responsible – and liable – for these procedures in a press shop.
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.
Die Safety Block Calculations
Three factors need to be determined to guide the selection of safety blocks: static load, block length and block size.
Determine static load – The static load that the die safety block will support is determined by adding the actual weights of the press slide and slide components, such as the ram-adjustment assembly, connection rods or pitman arms, 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.)
Static Load Formula:
(Press Bed Area (square inches) x Shut Height (inches))/(Cubic Inches/Cubic Feet (1,728 cubic inches/cubic foot constant))
Cubic feet displaced x 2,000 lb/cubic foot = Total Static Load
Press Bed Area = 48 inches x 96 inches
Shut Height = 24 inches
(48 x 96 x 24)/1728 or 110,592/1728 = 64 cubic feet
64 cubic feet displaced x 2,000 lb/cubic foot = 128,000 Total Cubic Static Load
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, and not the distance between the bolster and slide. This gives the maximum safety block length. To determine the 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.