ASME B107.47M-1998 — Metal Chisels: Safety Requirements

⛏️ ASME B107.47M-1998, an American National Standard published by the ASME B107 Committee, establishes safety requirements for the design, construction, testing, and use of hand-held and handled metal chisels. Metal chisels are intended specifically for cutting and shaping metal objects, and the covered types include the cold chisel, cape chisel, concave chisel, splitting chisel, diamond point chisel, and half-round chisel. The Standard was developed by the Striking and Struck Tools Subcommittee, its earlier version was ANSI/HTI B209.1-1991, and it was approved as an American National Standard on July 16, 1998.

1. Scope and General Framework 📌

Section 1.1 (Scope) states that the Standard provides safety requirements for hand-held and handled metal chisels intended specifically for use in cutting and shaping metal objects. The covered types include:

• Cold chisel: the most general type, used to cut thin plate, remove burrs, and cut slots;
• Cape chisel: a narrowed edge used to cut keyways, oil grooves, and narrow slots;
• Concave chisel: an arc-shaped edge used for circular grooves;
• Splitting chisel: used where powerful cutting is required, e.g., splitting nuts;
• Diamond point chisel: a diamond-shaped point used to clean corners and deburr;
• Half-round chisel: a semicircular edge used for oil holes and circular grooves.

The Standard explicitly excludes power-driven chisels — those belong to power-tool standards. As with the rest of the B107 series, only safety-relevant design details are specified, not manufacturing processes; the Standard also serves as a basis for manuals, posters, and training, and may be referenced by regulatory bodies.

2. Design Requirements and Materials 🔧

Section 4 (General Requirements) comprises Design (4.1), Materials (4.2), Mechanical Properties (4.3), and Tests (4.4). Design requirements include a struck face of adequate area with a chamfer (to prevent hammer slippage and edge spalling), a body cross-section and taper that ensure strength, and a bevel angle that ensures cutting capability.

3. Test Methods 🧪

Section 4.4 specifies the tests, the core one being the static force test (Fig. 3 of the Standard): the chisel is mounted in the defined fixture and a static force is applied at the cutting edge in the prescribed manner to verify the load-carrying capacity of the edge and body under cutting conditions.

• Arrangement: per the typical static force test rig of Fig. 3, with fixed support span and loading position;
• Loading: load to the specified force or deformation;
• Acceptance: after testing, the edge must show no safety-relevant spalling and the body no noticeable bending or cracks;
• Hardness verification: Rockwell hardness is measured at specified positions on the edge and body per ASTM E18 to confirm heat-treatment quality.

4. Safety Requirements and Limitations of Use 🛠️

• Eye protection: chips fly at high speed when chiseling metal; both operators and bystanders must wear eye and face protection per ANSI Z87.1;
• Hammer matching: use a hammer matched to the chisel size, with a striking face larger than the chisel’s struck face, to avoid glancing blows;
• Mushrooming checks: a mushroomed struck face must be ground back or the chisel discarded immediately — mushroom fragments are a leading source of hand and eye injuries;
• Correct gripping: grip handled chisels by the handle; hold hand-held chisels at the mid-to-rear of the body, never in front of the edge;
• Workpiece clamping: clamp the workpiece securely (e.g., in a vise); never hold it by hand;
• Marking and training: safety signs per ANSI Z535.4 and training per this Standard.

5. Engineering Practice Essentials ⚙️

• Selection by job: cold chisel for cutting thin plate, cape chisel for narrow slots, diamond point for corners, half-round for circular grooves;
• Resharpening: regrind at the original bevel angle, cool thoroughly to prevent annealing, and re-verify hardness;
• PPE programs: establish chiseling work procedures with goggles, screens, and anti-slip gloves;
• Procurement acceptance: request hardness data and static force test reports as the basis for incoming inspection.

6. Frequently Asked Questions ❓