In CNC and machining operations, accurately determining the position of the workpiece on the machine is the most fundamental step for precision machining. Workpiece zeroing probes (edge finders), used for axis zeroing, allow workpiece reference points on the X and Y axes to be defined conveniently and with high accuracy.
Watch Temak Teknik’s informative video below covering probe types and application steps:
Types and Features of Edge Finders
Different probe solutions are used depending on shop-floor needs and machine infrastructure:
1. Mechanical Edge Finders
Mechanical edge finders consist of a two-stage cylindrical body combined with a spring mechanism. They are divided into three groups according to their material:
- Steel Edge Finders: Offer an economical solution. However, they may become magnetised over time due to friction.
- Stainless Steel Edge Finders: Eliminate the risk of magnetisation, providing more stable measurement.
- Ceramic Edge Finders: Extremely high wear resistance. Their shock-resistant, non-magnetic design ensures a long service life.
2. Light and Sound Edge Finders
On conductive workpieces, these systems complete an electrical circuit on contact and give both a visual (LED) and an audible (buzzer) signal:
- No Spindle Rotation Required: Measurement is made by direct contact without rotating the spindle (while stationary).
- High Precision: Provides accuracy at the 0.005 mm (5 micron) level.
- Note: For light/sound edge finders to work, the workpiece and machine table must be conductive (mechanical edge finders should be preferred for plastic or insulated materials).
How to Zero Correctly with a Mechanical Edge Finder
To zero a part to 0.01 mm (1%) accuracy with a mechanical edge finder, follow these steps:
- Speed Setting: Mechanical edge finders are used with the spindle rotating. The recommended speed range is 400 – 600 rpm (ideally 500 rpm). Higher speeds can cause the spring mechanism to fly apart and damage the equipment.
- Gradual Approach: Approach the workpiece using the handwheel. At first contact, the lower tip of the probe rotates eccentrically (wobbling).
- Kick-Off Point (Reference Moment): As contact continues, the axial wobble disappears and, at the moment it is exactly on axis, the lower tip makes a sideways “kick-off” movement. Stop the axis movement as soon as this kick is observed.
- Defining the Coordinate: Taking the position at the moment of kick-off as reference, the radius of the probe tip used (e.g. 5 mm for a Ø10 mm tip) is added to or subtracted from the axis value.
Critical Points to Observe in Use
- Do Not Use on the Z Axis: Edge finders are designed only for horizontal contact on the X and Y axes. Applying vertical pressure on the Z axis will break the probe and damage the machine.
- Observe the Speed Limit: The speed limits specified by the manufacturer for mechanical edge finders must not be exceeded.
- Magnetisation Check: To prevent measurement errors, it is recommended to demagnetise steel edge finders periodically or to choose ceramic/stainless models.
For edge finder types and technical details that provide fast and precise zeroing of your workpieces, visit our website temak.com.tr and get support from our expert team.