Other Applications
Using non contact measurement sensors, AIS develops systems for measurement, inspection and test of manufactured components - either on the production line or as part of a separate test station for periodic inspections on samples from the line.
Systems are built using standard hardware, software and non-contact sensors such as laser gauges and LVDTS.
Example applications are detailed below:
- On-Line measurement of brake pads.
- Roundness and concentricity of hole saws.
- Critical dimension measurement of vacuum pumps
On-line measurement of brake pads
Brake pads are subject to stringent dimensional quality requirements. AIS has developed an on-line measurement system for 100% test.
Using a magnetic drag arm, brake pads are automatically removed from a production conveyor system onto a dedicated test system conveyor where they are aligned and moved through a laser profile measurement system. AIS use the Micro Epsilon LLT2800 which offers the best performance sensor of its type.
The measurement conveyor is split into two sections using a 'knife edge principle' to provide laser access to the product from above and below at the same time. This means that the lasers make a differential reading which removes the effects of vertical movement.
The system is controlled by a PC that captures a complete profile of the brake pad and then calculates thickness, flatness and parallelism. Measurement results are compared to pre-defined limits and a GO/NOGO decision made in less than 2 seconds. The pads that meet the criteria are diverted to a storage table for packing. Failed units are sent to a reject bin.
Key facts:
- 100% on-line test of components
- The LLT2800 gauge provides complete detailed profiles for analysis
Roundness and concentricity of hole saws
Holes saws are manufactured from a cut sheet which is then bent around a mandrel and welded both to form the circular shape and to attach the blade to the base plate. The requirement is to check that the holes saws are both round and concentric. This is to ensure proper cutting performance when used. Testing of the saws is on a sample basis from each of the manufacturing cells.
AIS developed a test rig for rotating the hole saw and taking laser measurements. A picture of the test rig is shown.
The hole saws are placed on a high accuracy rotary table using an installation plug that ensures that they are mounted centrally and the rear plate sits flat on the surface.
The saws vary in dimension from approximately 15mm to 150mm. This means that in order to achieve the required measurement accuracy, the rotary table is mounted on an X axis table thus enabling positional adjustment of the laser. Additionally, the rig is mounted on an elevating stage so that measurements can be taken at the top and bottom.
The Micro Epsilon ILD1400-10 gauge has a resolution of 5mm when providing readings a 1kHz. The system calculates the size and relative positions of the minimum circumscribed, maximum inscribed and least squares circles to define the offset of the cutter from its own centre (eccentricity = concentricity/2) and the roundness error using the minimum zone method. The display below shows a of part of the measurement system display
Concentricity and roundness are displayed after measurement of a full rotation
For clarity, the display is shown with a 25x magnification of the roundness error.
The green circle shows the measured values. The red circles show the inscribed and circumscribed circles. The blue line shows the least squares fit.
Key facts:
- Non contact measurement
- Standard system components removes requirement for expensive dedicated machines
Critical dimension measurement of vacuum pumps
BOC Edwards makes scroll pumps. These are efficient vacuum pumps that are
used in a wide range of industrial and scientific applications. As part of
the manufacturing process a critical dimension - between the front face of
the scroll and the main housing - must be measured as the pump is rotated.
This then determines the size of a shim to be fitted.
AIS's laser-based system - capable of resolving to better than 5µm - enables the manufacturing staff to perform a simple test and determine the correct shim to fit to a given pump. All test data is automatically recorded against the pump type and serial number (read directly from a label on the pump using a bar code scanner).
Key facts:
- AIS provided a complete measurement jig for mounting the laser on the
pump
- Simple step by step test sequence provided via the computer