Millwright Quiz

Since we'll be talking about pasta factories, and one of the things I have recently done at a pasta plant was installing ingredient weigh scales, this quiz will be about levelling. Any machine installation is for nothing if the thing isn't level.

Millwrights use many tools and methods to level machinery, from the basic torpedo level, through to master levels, to piano wire and line levels, water levels, and optical levelling tools such as tilting levels, dumpy levels, and lasers. The accuracy usually ranges from 5 thou' (0.005") to a tenth of a thou' (0.0001"), depending on the requirements of the project.

Here are the basic steps to levelling most installations:

1. If the machine has a "soft pad" (a foot or levelling point not in contact with the base), pack that up first.
2. Place the level in one direction across the machine (eg, north-south) and determine the shims required in this plane.
3. Place the level the other way across the machine (eg, east-west) and determine the shims required in this plane. This will be additive to the shims in step 2.
4. If you have made an error, remove the shims and restart your calculations, because it is best to have no more than three shims per pack. More than that can cause errors due to compression and expansion of the spaces between them.

Quiz:
You have a machine which is 5' between levelling points, north to south, and 3' between levelling points, east to west. When you put a 12" level on it N-S, the level requires 0.015" on your feeler gauges under the north end to center. When you place this level on it E-W, you use 0.005" of feelers under the east edge. How much shims do you need to put under each foot of the machine?

This month's feature industry is pasta manufacturing. Normally you may not think of food production as a place to see much machinery in action, but in fact this industry is often highly mechanized. This approach keeps handling down, resulting in less contamination--an "untouched by human hands" final product. Mixers, ingredient silos, weigh scales, conveyors, packaging equipment...these are just some of the things which require millwrights in these plants.

Pasta is made from wheat, in fact from a special kind of wheat called durum. The durum is ground into semolina flour. Then things may be added to it, such as vitamins, colors, vegetable flavours. Next it is mixed with water into dough, and pressed to shape (spaghetti, macaroni, etc.) It is then dried and cooled, and finally stored or packaged. Sounds simple, but it is subject to many checks and inspections along the way, because each step is really a rather exacting process.

Here are some links that will give you more information:

Italpasta's site explains the process details clearly:
http://www.foodexplorer.com/manu/industry/FI09733.htm

Here's another site which answers "how is pasta made?"
http://www.crop.cri.nz/foodinfo/millbake/pasta.htm

The site of FANUC Robotics has a great story explaining how and why they were involved in some machinery installation at Primo Foods:
http://fanucrobotics.com/b/b1/b1i2_ct.html

Answer to the Millwright Quiz Question

In the North-South plane, the distance between feet is 5'. Since the 12" level needed 0.015", the same ratio applies to the machine. Therefore, 5' being 60", you will need 60/12 x 0.015 = 0.075" shims on both north feet.
East to west, 3 feet is 36", so the formula is 36/12 x 0.005 = 0.015" on the east feet.
Therefore in total, put 0.075" under the NW foot, 0.015" under the SE foot, and 0.075 + 0.015 that is, 0.090", under the NE foot.

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