April 2011 / Volume 63 / Issue 4|
Storing and handling raw material
By Tom Lipton
Because labor is typically the most expensive component of any job, anything you can do to shorten the labor path during a job will have a short payback period. A good example is in materials storage.
Every shop must store some raw materials. The trick is to store workpieces in such a way that you can get to the desired piece with minimal effort. Here are some tips to effectively handle and store raw material.
Cut 20 ' bars in half for easier handling. It depends on the type of work a shop performs, but rarely are full 20 ' bars utilized without cutting. In small shops, 20 ' lengths can be difficult to handle and it is time consuming to cut off a short length. This challenge continues until the material is short enough to be efficiently handled. The time to cut the bar is when it comes in the door from the supplier.
Courtesy of All images: T. Lipton
Carts used for moving bar stock around the shop should be the correct height for the horizontal bandsaw so material can be pushed into the saw as soon as it is unloaded. Support tubes should also be set up so you can load and unload bar stock with a forklift directly from the delivery truck.
Organize material drops by length, such as full bars, partial bars and stubs. Most people will try to use the material with the easiest access before pulling out the full-length materials. If you provide and maintain a system for finding the optimal stock in the speediest manner, you shorten the job. This is proven time and again when we filter our racks and bins. The size of the keepers gets smaller and smaller until they just disappear.
Occasionally inventory and organize the material storage area. This job allows apprentices and helpers to get acquainted with the shop’s raw material inventory.
Beware of packrats. Machinists and welders are natural scrounges. Want proof? Look under the workbenches and in the nooks and crannies of their work areas. Some materials and leftovers really need to be scrapped to run an efficient shop.
Get rid of materials that cannot be easily identified. If you don’t know what it is, how can you use it? When in doubt, toss it out.
Certain forms of scrap and material drops are virtually useless. Long, thin strips of sheet metal and triangles cut from almost anything are two examples that can hit the scrap bin right out of the gate.
On the other hand, almost all circles and discs are valuable. Unless your processes generate a large quantity of disc-shaped parts, these should always be saved.
It is a challenge to maintain material identification in a job shop. Each time a piece of material is cut, there is a risk of losing the identity trail.
It’s everyone’s responsibility to make sure the identity chain does not get broken. Keep marking tools readily available in areas where materials are stored and rough cut. Put identifying marks on both end surfaces of bars.
Engrave or mechanically stamp the material type directly on the bar end. Tags fall off and ink smears. Labels are next to useless because they are placed on the side of the material where other material sliding in the rack can obliterate the identification. Somebody also has to remove the sticky labeling substance at some point. When you mark the end surfaces of material, it fits in collets and vises; the first cut in the machine removes the engraving.
Don’t use obscure internal company terminology or secret codes for common materials. Use the same terminology suppliers use. For certified materials, include the purchase order number the material was purchased with. This information helps when tracking down copies of test reports and conformance data.
Understand that metal supplier color codes are unreliable. There is no real color standardization in the metal supply industry. These should only be used as a generalization or identification when combined with another method.
Store flats on edge in the vertical orientation. Graduate them by width to make inventory and removal easier.
Small rounds should be stored in tubes so they don’t slip between rack dividers. Alternatively, you can form simple sheet metal trays for the slots that contain small materials. This keeps the more flexible materials from drooping and missing the rack supports. CTEAbout the Author: Tom Lipton is a career metalworker who has worked at various job shops that produce parts for the consumer product development, laboratory equipment, medical services and custom machinery design industries. He has received six U.S. patents and lives in Alamo, Calif. Lipton’s column is adapted from information in his book “Metalworking Sink or Swim: Tips and Tricks for Machinists, Welders, and Fabricators,” published by Industrial Press Inc., New York. The publisher can be reached by calling (888) 528-7852 or visiting www.industrialpress.com. By indicating the code CTE-2011 when ordering, CTE readers will receive a 20 percent discount off the book’s list price of $44.95.
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