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ISO 28927-7:2009 — Hand-held portable tools — Vibration test for nibblers and shears
Laboratory measurement of hand-transmitted vibration for sheet metal cutting tools | Engineering guide
Introduction to ISO 28927-7
ISO 28927-7:2009 specifies a laboratory method for measuring hand-transmitted vibration emission at the handles of hand-held power-driven nibblers and shears. Replacing ISO 8662-10:1994, this standard covers machines used for cutting sheet metal through reciprocating action, driven pneumatically, hydraulically, or electrically.
Nibblers cut by removing small pieces (nibbles) of material using a reciprocating punch and die, while shears cut by moving a blade past a fixed blade. Both produce distinct vibration profiles requiring specific measurement approaches.
Key Technical Requirements
Measurement and Operating Conditions
Vibration must be measured simultaneously in three orthogonal axes at each hand position. The integration time shall be at least 8 seconds during stable cutting operation. The standard uses real working conditions: cutting standardized sheet metal of specified thickness and material.
| Parameter | Nibblers | Shears |
|---|---|---|
| Test material | Steel sheet (specified thickness) | Steel sheet (specified thickness) |
| Cutting speed | Manufacturer rated speed | Manufacturer rated speed |
| Feed force | As required for stable cutting | As required for stable cutting |
| Integration time | ≥ 8 s | ≥ 8 s |
The reciprocating cutting action of nibblers creates distinct vibration peaks at the cutting frequency. Care must be taken to ensure the measurement system frequency range adequately captures these components.
Engineering Design Insights
Nibblers and shears present unique vibration measurement challenges because the cutting process itself creates intermittent loads that modulate the vibration signal. The standard addresses this by specifying a minimum integration time of 8 seconds, ensuring that multiple cutting cycles are captured in each measurement.
The transducer mounting is particularly critical for these tools due to the high acceleration levels and the presence of reaction forces from the cutting process. Anti-vibration handles, if fitted, must be measured at the prescribed transducer locations on the handle itself.
Three skilled operators each perform five test runs. The coefficient of variation must not exceed 0.15, and the standard deviation must not exceed 0.3 m/s² for valid results.
Frequently Asked Questions
Q: What is the difference between a nibbler and a shear?
A: A nibbler removes material by punching small pieces sequentially, creating a kerf. Shears cut by blade action, similar to scissors, without removing material.
A: A nibbler removes material by punching small pieces sequentially, creating a kerf. Shears cut by blade action, similar to scissors, without removing material.
Q: Can this standard be used for electric and pneumatic tools interchangeably?
A: Yes, the standard applies regardless of power source.
A: Yes, the standard applies regardless of power source.
Q: How does cutting speed affect vibration measurements?
A: Higher cutting speeds generally produce higher frequency vibration. The standard requires testing at the manufacturer rated speed with specified material thickness.
A: Higher cutting speeds generally produce higher frequency vibration. The standard requires testing at the manufacturer rated speed with specified material thickness.
