Grinding Wheel Guard Strength Testing Device

The Grinding Wheel Guard Strength Testing Device is a specialized testing equipment designed for the strength testing of angle grinders and straight grinders' guards as specified in Chapter 20 of GB 3883.3/IEC60745-2-3/EN60745-2-3 "Safety of Hand-held Motor-operated Electric Tools — Part 2: Particular Requirements for Grinders, Polishers, and Disk-Type Sanders". Its technical specifications comply with the relevant requirements of GB 3883.3.

1 Applicable Standards and Standard Requirements

1.1 Applicable Standards

GB 3883.3/IEC60745-2-3/EN60745-2-3 "Safety of Hand-held Motor-operated Electric Tools — Part 2: Particular Requirements for Grinders, Polishers, and Disk-Type Sanders"

1.2 Relevant Clause Requirements of the Standard

The requirements for grinding wheel guard strength testing in GB 3883.3 are detailed in Chapter 20.

Chapter 20 Mechanical Strength

20.101 All guards recommended by the manufacturer shall have sufficient mechanical strength to prevent fragments of the grinding wheel from flying towards the operator in the event of wheel breakage.

Compliance is checked by submitting three samples of the recommended guard for testing according to 20.101.1 to 20.101.4. With the manufacturer's agreement, the test may be carried out on three guards, but on fewer than three grinders. After the test, the tool shall meet the compliance requirements of 20.101.5.

20.101.1 The guard is firmly mounted on the grinder as instructed. If the guard is adjustable, it shall be positioned to cover the wheel as far as possible, either 30° (±10°) opposite the direction of wheel rotation beyond the centerline or symmetry line of the wheel, or at the maximum setting if the adjustment range is less than 30° (see Figures 106a and 106b).

A wheel of diameter equal to the rated capacity of the grinder and of the maximum thickness recommended by the manufacturer shall be mounted on the spindle as instructed.

The grinder shall be run at no-load at rated voltage for at least 5 minutes. Measure and record the wheel speed.

20.101.2 The wheel specified in 20.101.1 shall be cut with four equally spaced notches. For Type 27, 28, and 41 wheels, the notches are cut radially from the outer edge toward the center (see Figure 107). For Type 6 and 11 wheels, the cutting starts from the working face toward the mounting end (see Figure 108).

Each notch shall be no wider than 2.5 mm. The notches shall be deepened such that the wheel disintegrates under centrifugal force generated at a speed equal to or greater than the speed established in 20.101.1 or 90% of the grinder's rated speed (whichever is higher). Mount the notched wheel on the spindle as instructed.