Example 3 - A Food Sorting Machine:- Delivery Chute

This is an aluminium alloy component in a food sorting machine. The product falls under gravity along the inclined chute and, to allow efficient and consistent sorting by 'magic eye' detectors, it must pass at a constant speed. hence, the surface needs to be smooth, abrasion resistant and be food approved.
 

Entering details of the consultation

Enter as in the first examples. Call it a 'Chute'.

Choosing the type of contact

Again, the first consultation screen is very important. You are asked to describe the type of contact and, based on your choice, the programme will tailor its subsequent questions.
You will see a screen like this:
 

In this case, the problem is one of a product (the food) in contact with your component. There is no other engineering component involved. Hence, you should click on Contact with a Product and change it to a tick. Then press OK.
The programme will follow the sequence of screens shown as the centre line on the facing page.

Choosing the substrate material

Click on aluminium alloy.

Entering the contact loading conditions

Firstly, note that the computer has skipped the 'Counterface? screen. You will be asked about this later.
For the loading conditions, this is a very gentle application. The loads are light, there is no question of erosion or massive impacts. Tick on 'sliding' to show that the food is moving along the chute. Although some of the product may roll, it is not appropriate to tick 'rolling' here; that is aimed at bearings or other components where rolling components predominate.

Entering more contact conditions

The contact is not lubricated. You have specified the need for easy sliding, but leave the 'Low Friction' box with a cross for now; you can come back to it later and look at the effect of changing it.
The load between the food and the chute is very light, so there is no 'Heavy Loading'. When you press OK, the computer will assess the problem as Low Stress Abrasive Wear and ask you what products is involved.

Specifying the product being handled

This is a new screen; one you haven't seen before. It asks you what is your product and from the answer it will determine how hard the surface of the component should be made to resist the Low Stress Abrasive Wear.
 
Click on 'Dry Food Product' and press OK.

Specifying the hardness

The programme has entered the value for you; 450Hv. You can change it if you wish, but in this situation the programme is best believed.
Leave this screen by pressing OK.
 

Specifying the required surface finish

This is up to you; the surface roughness may have a significant affect on the way the product slides. Enter 0.5µ for both the before and after surface finish, specify No to post-finishing and specify No to allowing surface roughening.
 

Selecting partial coating options

The areas in contact with the food need to be coated. The rest of the component doesn't matter either way. Click on Defined areas must be coated.
 

Entering the operating temperature

It's a room temperature operation. Put 30oC in the two boxes.
It's not a high precision component, but it is made in aluminium alloy, so select 400oC as the maximum permitted processing temperature.
 

Specifying chemical contamination

There is none. Click on OK.
 

Requirements for mould release or food approval

The coating must be food approved. Click on it to change it to a tick and press OK.
 

Describing the component's geometry

It has no unusual features. Move on.
 

Entering the component dimensions

The chute is 1000mm long and 30mm wide. Enter the values and move on.
 

Examining the results

 
The programme recommends any of 19 processes based around anodising, electroless nickel or hard Cr.  Click on "wear" to show the ranking according to that property.
If you feel that the friction needs to be low under all circumstances, then some of the above solutions will be better than others. Click on the DATA button and select 'Low Friction Required' from the list. When the screen comes up, change the selection form a cross to a tick and press OK.
Now you will see that only ten processes are recommended as giving the lowest friction.
Try the DATA button again, this time looking back at the allowable processing temperature. Reduce it to 300oC (maybe you are worried about distorting the chute). Now you will see that only one process is suitable; with the composite anodising process by Poeton (350R) being the only coating which provides food approval, low friction, low processing temperature and resistance to wear by the food.
 

Poeton Industries Ltd. Head Office, Eastern Avenue, Gloucester GL4 3DN, England, UK   Tel: 01452 300500  Fax: 01452 500400
Production facilities in Cardif & Gloucester and in Wisconsin. USA.