Quality control is a vital aspect of any manufacturing or assembling process. As such, sampling and visual inspection are an integral part of the production.
It is difficult to make firm recommendations about inspection areas because the tasks are so very different. They can vary from inspecting the paint finish on a luxury car to microscopically soldered joints on a printed circuit board or testing for leaks in a hydraulic system.
Clear materials such as glass require different techniques such as backlighting, maybe with the addition of a grid of lines, to highlight imperfections in the thickness or flow stresses.
The three inspection lamps below all have magnifying lenses and produce a small area of high illumination. All are fully adjustable and have a variety of mounting methods such as desk clamps.
Both the Wave and KFM luminaires are also available in ESD, (electro-static discharge), versions. These are very commonly required in the electronics industry.
The emphasis in this Design Clinic is on the adjustable inspection lamps. Of course, you will also need general lighting for other activities and tasks in the inspection area.
For this, we have used the Glamox C63-R. This is an IP55 recessed unit and we have used the version with a micro-prismatic glass panel. There is also the option of opal or polycarbonate panels. It can also be colour tunable where you want to vary the CCT throughout the day.
Objects which can be inspected on a bench are usually small. Similarly, the faults or blemishes to be revealed are even smaller. Common examples are printed circuit boards or finely machined metal parts.
For these, some form of magnification is needed. The Wave has a rectangular lens with light sources on both sides. A useful feature is that the left and right side LEDs can be switched independently so that irregularities in height can easily be observed. I.e. lighting from one side will cause a visible shadow if there are any dips or blemishes. The beam is wider in one direction than the other which is useful for inspecting rectangular products.
The lens is crown glass and measures 175 x 108 mm (7” x 4.25”). The standard version has a 3.5 or 5 dioptre lens (188% or 225% magnification).There are optional additional lenses to produce 4D, 6D, 10D magnification.
Tech spec A
- LuminairesWave LED with magnifying lens
- Light output764lm
- CRI and CCT80, 4000K
- Wattage per luminaire 13W. Three-step dimming.
This is an all-round, multi-purpose inspection lamp. Typical applications range from medical uses such as chiropody, industrial fine machining, textile inspection or even simply as a reading or desk light.
The KFM has a 127mm (5”) diameter circular lens with the choice of 3.5 or 5 dioptre magnification. Like the Wave, there is the option of additional magnifying lenses.
Illumination comes from the two semi-circular LEDs located in the rim of the magnifying lens. This has a handle so you can easily adjust the angle and height of the head without obscuring the LEDs.
The KFM is completely dimmable from 1- 100% and there is an inbuilt timer that can be set to switch off automatically after 4 – 9 hours.
Tech spec B
- LuminairesKFM LED
- Light output674lm
- CRI and CCT80, 4000K
- Wattage per luminaire 11W. Dimmable 1- 100%.
A useful inspection technique is to use ultra-violet light. Many materials, such as oils, will fluoresce under UV light. You can also add a fluorescing dye to a liquid. This can be a good way of testing seals and joints where any leakage becomes easily visible under UV light. Almost the reverse technique can be used on surfaces such as conformal coatings where a crack, blemish or pin-size hole will be revealed as being “black”.
The source is an LED producing UV-A at 365nm and emits a dark purple light. The magnifying lens on the Wave means that even hairline cracks can be revealed.
One final point is that whenever ultra-violet light is used, you should take precautions to prevent excessive exposure to eyes or skin.
Tech spec C
- LuminairesWave UV-A
- Light outputN/A
- CRI and CCTN/A
- Wattage per luminaire 13W