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Subchapter 7. General Industry Safety Orders
Group 8. Points of Operation and Other Hazardous Parts of Machinery
Article 56. Metal Working Machines

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§4239. Forging Machines.

(a) Definitions.

Bolt-Headers. The same as an upsetter or forging machine except that the diameter of stock fed into the machine is much smaller, i.e., commonly three-fourths inch or less.

Drop Hammers. Drop hammer means a hammer in which the force of the blow is developed entirely by gravity.

Forging Presses. A class of forging equipment wherein the shaping of metal between dies is performed by mechanical or hydraulic pressure, and usually is accomplished with a single work stroke of the press for each die station.

Forging. The product of work on metal formed to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. Forging hammers, counterblow equipment and high-energy-rate forging machines impart impact to the workpiece, while most other types of forging equipment impart squeeze pressure in shaping the stock.

Forging Rolls. A class of auxiliary forging equipment wherein stock is shaped between power driven rolls bearing contoured dies. Usually used for preforming, roll forging is often employed to reduce thickness and increase length of stock.

High-Energy-Rate Forging Machines. A class of forging equipment wherein high ram velocities resulting from the sudden release of a compressed gas against a free piston impart impact to the workpiece.

Open Frame hammers (or Black-Smith Hammers). Hammers used primarily for the shaping of forgings by means of impact with flat dies. Open frame hammers generally are so constructed that the anvil assembly is separate from the operating mechanism and machine supports; it rests on its own independent foundation. Certain exceptions are forging hammers made with frame mounted on the anvil; e.g., the smaller, single-frame hammers are usually made with the anvil and frame in one piece.

Ring Rolls. A class for forging equipment used for shaping weldless rings from pierced discs or thick-walled, ring-shaped blanks between rolls which control wall thickness, ring diameter, height and contour.

Rivet Making Machines. The same as upsetters and bolt headers when producing rivets with stock diameter of 1-inch or more. Rivet making with less than 1-inch diameter is usually a cold forging operation, and therefore not included.

Steam Hammers. A type of drop hammer where the ram is raised for each stroke by a double-action steam cylinder and the energy delivered to the workpiece is supplied by the velocity and weight of the ram and attached upper die driven downward by steam pressure. Energy delivered during each stroke may be varied.

Trimming Presses. A class of auxiliary forging equipment which removes flash or excess metal from a forging. This trimming operation can also be done cold, as can coining, a product sizing operation.

Upsetters (or Forging Machines, or Headers). A type of forging equipment, related to the mechanical press, in which the main forming energy is applied horizontally to the workpiece which is gripped and held by prior action of the dies.

(b) General.

(1) Thermostatic control of heating elements for lead melting shall be provided to maintain proper melting temperature (620 to 700 degrees Fahrenheit) and prevent overheating.

(A) A covered container shall be provided to store dross skimmings.

(B) Equipment shall be kept clean, particularly from accumulations of yellow lead oxide.

(c) Drop Hammers.

(1) Drop hammers shall be equipped with safety stops which will hold the hammer in the elevated position.

(2) Stops shall be of a design that requires the hammer to be lifted to release the safety stops.

(3) The ram shall be blocked when dies are being changed or other work is being done on the hammer. Blocks or wedges shall be made of material the strength and construction of which meet or exceed the specifications and dimensions shown in Table FM-1.

Size of         Square             Minimum allow-      Maximum static                    Maximum recom-            Maximum 
timber         inches in           able crushing        load within        Safety        mended weight of          allowable 
inches1      cross section        strength parallel    column range3       factor        forging hammer            length of 
                                  to grain, p.s.i.2                                      for timber used          timber, inches 
4 x 4             16                   5,000               80,000            10               8,000                  44 
6 x 6             36                   5,000              180,000            10              18,000                  66 
8 x 8             64                   5,000              320,000            10              32,000                  88 
10 x 10          100                   5,000              500,000            10              50,000                 100 
12 x 12          144                   5,000              720,000            10              72,000                 132 

1 Actual dimension.

2 Adapted from U.S. Department of Agriculture Technical Bulletin 479. Hardwoods recommended are those whose ultimate crushing strengths in compression parallel to grain are 5,000 p.s.i. (pounds per square inch) or greater.

3 Slenderness ratio formula for short columns is L/d = 11, where L = length of timber in inches and d = least dimension in inches; this ratio should not exceed 11. -------------------------------------------------------------------------------------------------------------------------------------

(4) To prevent kickback injury tong handles shall be of sufficient length to permit them to be held at either side of the employee.

(5) Tongs shall have blunt handle ends.

(6) Where required, oil swabs, or scale removers, or other devices to remove scale shall be provided. These devices shall be long enough to enable employees to reach the full length of the die without placing hand or arm between the dies.

(7) Die keys and shims shall be made from a grade of material that will not unduly crack or splinter.

(8) All manually operated valves and switches shall be clearly identified and readily accessible.

NOTE: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.


1. Repealer and new section filed 10-25-74; effective thirtieth day thereafter (Register 74, No. 43).

2. Amendment of subsection (b)(7) filed 7-8-85; effective thirtieth day thereafter (Register 85, No. 28).

3. Amendment filed 12-16-85; effective thirtieth day thereafter (Register 85, No. 51).

4. Change without regulatory effect filed 7-17-90 to correct State Printing Plant error made obsolete by Barclays printing of the Code (Register 90, No. 40).

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