A profile projector is an optical measuring instrument used in metrology and quality control. This device allows the shadow of the part to be measured to be projected on a screen which is then used by the operator to perform the measurements. It’s the principle of Chinese shadows, but it still works very well today.
Plastiform markets products that are very suitable for this type of device and many of our users use a profile projector, but how does it work?
Modern profile projectors
Since the invention of profile projectors, their technology has evolved significantly to meet quality control needs. Today, controllers require efficient, stable and easy-to-use profile projectors. The most advanced machines thus have a whole bunch of features very easy to set up, we are far from the first models, but the principle has not changed.
The specifications of modern profile projectors
Today, optical measuring devices are among the most reliable measuring devices. Thus, manufacturers ensure that their machines are equipped with state-of-the-art equipment:
- Guidance system and laser pointer, for easier machine handling.
- Internal software to assist the operator in his measurement and ensure maximum accuracy.
- Quick part positioning systems.
In addition to this, the devices are built with top quality materials, for example Sylvac’s Visio 200 is made of granite, a heavy and very stable rock, which ensures the machine a high weight and a long life table.
Lighting and projection with a modern profile projector.
Being able to change or adjust the lighting of a profile projector allows you to better adapt your machine to the measurement you need to make. Diascopic lighting (lighting from below), for example, will help you to measure contours or perform transparency checks. On the other hand, coaxial episcopic lighting (top lighting) will allow you to make better use of large enlargements, for example to control blind holes or highly reflective parts.
On modern machines, the lighting is very easy to adjust. The one we use internally, for example, the Visio 200, is very robust, we can switch from one mode to another directly from the software.
To measure Plastiform impressions, it is often necessary to use Diascopic lighting (Backlight – the light below), it is more suitable for the measurement process we have put in place !
Profile projector and Plastiform, how to do it ?
Plastiform is an impression taking technology developed specifically for checking the dimension (or surface finish) of parts. Plastiforms are specially made for quality control in the industry. Their popularity is growing, they are highly appreciated by the players in the field because of this specificity.
Plastiform, what is it? Why use it with a profile projector ?
The technology is very simple to use, the plastiforms are polymers originally in two components. Mixing the two components together leads to a chemical reaction: polymerization. It is this chemical reaction that allows the product to harden and capture the properties of the part to be measured. Cured products have several properties that are very interesting for the quality controller:
- It is easy to extract: some products are very flexible, so it is possible to extract them from the part, without damaging either the part or the impression.
- They are shape memory: pulling on the product does not deform the impression, it always returns to its original state.
- Absence of dimensional shrinkage: During polymerization, there is no dimensional shrinkage. The impression is accurate to the micrometer.
- The impressions can be decoupled: You can easily cut the impression.
And it is this last property that makes Plastiform a technology very suitable for profile projectors! Not only are you able to control areas that are inaccessible to your measuring instruments, but you can also cut a two-dimensional profile of the impression, without damaging it, to control it by projection.
Placement of a Plastiform impression on a profile projector
When you extract your impression, it will be in three dimensions: the exact negative of your part. Slicing a profile in two dimensions can be difficult at first, but don’t panic, we’ve thought of everything!
In response to this need, Plastiform has had a custom-made Double Blade Cutter forged with two parallel, hand sharpened blades. This cutter, with its cutting guide, allows you to make a transverse slice of the impression in a single movement. This is what the result gives:
As you can see, the cutter makes a perfect slice in the impression. This slice is much easier to operate on a profile projector than the replica itself would have been. With lighting from below, simply place the impression flat on the tray of the profile projector and you can take your measurements.
The profile projector is one of the most widely used measuring devices in the industry, so their technology is very suitable for quality control. With a modern profile projector, you can easily adapt your control environment using all the options available to you.
To measure a Plastiform impression, you will usually need to use a profile projector. These machines allow a more precise control than contact control machines, and generally have a good price/quality ratio.
By following the process set up by Plastiform, you can take your impressions and then cut them with the Double Blade Cutter. This will provide you with a cross section of the negative of your part. The slices made with the Plastiform Cutter are very easy to use via a profile projector, especially if you can project light from below.