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FLEXO Magazine : January 2010
www.flexography.org JANUARY 2010 FLEXO 47 amount of a resource that is necessary to add value to your product. On the materials side, waste could be defined as the difference between what you purchase (and its cost to you) and what you actually deliver (and invoice) to your customer. Or consider this example: If you can make a 15 percent mar- gin on your production, then eliminating $150,000 of waste is equal to an additional turnover of $1,000,000. Here is the point: Waste directly equates to lost profit. Hence the title of this discussion: reducing your waste will cause your profit to increase. IDENTIFYING WASTE In order to reduce your waste, you first need to identify the causes and amounts of waste in your processes. This will open up opportunities to improve productivity, quality, com- petitiveness---and profitability. Do you know the causes of your waste? These causes can range from the handling and storing of materials to operator training and skills. Looking at the major causes of waste in a label environment, we can identify six primary components related to roll and material management: • Damage to rolls during shipping and handling. • Web breaks. • Butt rolls. • Unnecessary material stripped from the outside of rolls. • Material left on the core. • Material loss during down time associated with roll changes. DAMAGE TO ROLLS There are numerous ways in which raw material can become waste even before you get it onto the press. How old is your material when you get it from your supplier? How well is it wrapped and protected from temperature and humidity changes? How long do you stock material before use? Also, is your raw material storage all it should be? Are your rolls stored properly, not only for safety but to avoid damage? And how are they transported and presented to the press area? Here is something to consider: How clean is your floor? If a roll goes over a pebble that puts a 2mm deep dent in it, that small dent can equal eight wraps that need to be removed. Since one wrap on the outside of a 40in. diameter roll is about 10ft., that small dent can cause the loss of 80ft. of stock. That's immediate waste, and immediate loss of profit. Minimize your waste during shipping, storing and handling. Take greater care, and if necessary implement new practices, in material handling and storage. Evaluate your roll handling methods and consider investing in new, quality roll handling equipment. And insist on a clean operation. Cleanliness may not be next to godliness, but a lack of cleanliness is a precur- sor to lost profit. WEB BREAKS A web break has the same negative waste effects as any other press stoppage, in addition to the aggravation caused to the operator. Some of the typical causes may include: poor material or material that has been poorly handled (see above); poorly maintained equipment; inefficient splicing, whether manual or automatic; and tension control issues. Minimizing web breaks can be as simple as addressing these causes. Use a good quality material. Maintain your equipment adequately. Insist on a high splicing efficiency. (And by the way, make sure you are using the proper splic- ing tape for your material and your process.) And improve your tension control, so the press and auxiliary equipment is optimized for the materials you are running. BUTT ROLLS What do you do with a butt roll or partial roll when the press run is complete? Do you overproduce and bill to the custom- er? Or do you return it to stock and plan on using it later? Our informal research indicates that many converters will return a roll to inventory if it is longer than about 600ft. Less than that and it may be set aside or thrown out. Fact is, many converters have an area in their plant where butt rolls go to die---stacked, forgotten, and eventually dis- carded. Even if they 're paid for by your customers, could you make use of those rolls? Some printers/converters use butt rolls for clean-up and for doing preventive maintenance on their presses. The best way to use these butt rolls, however, is in profitable production. Depending on the timing and frequency of a particular job, you may be able to store the butt roll and retrieve it from stock for the next run. This becomes an attractive option if you have an automatic butt splicer on the press. In that case, you can start with the butt roll and, when it has expired, splice over automatically to a new roll. Also, consider using butt rolls during makeready. Makeready waste is often taken for granted, but you may be able to use butt rolls when readying a job with a similar stock. Some converters even substitute cheaper material during this stage before splicing over to the more expensive stock. Again, this may be an attractive option, but only when used with a butt splicer. SAMPLE PRODUCTION MODEL To evaluate the next three components of waste, it will be necessary to create a production model. Our model may be different from yours, but the principles are sound and can be applied to your own processes. Here is our model of a typical press: • Label printing press with web width = 16in. • Web length = 150ft. • Average speed = 150ft./min (including stops) • Hourly rate for this press $240/hr. $4/min. • Running 16hr./day, 5 days/week, 50 weeks Total of 4,000 hours/yr. • Roll changes = 16/day Total of 4,000 roll changes/yr. We will also make some conservative assumptions about the substrate used: • PS Label stock .006in. • 30in. outer diameter • 10,000ft./roll • 450lbs. roll weight • Weight per msi = 0.234lbs • Purchase price per msi = $0.35 Converters recognize that wasted stock in the press also means wasted inks, varnishes, laminate material and foil, as well as power and compressed air. The majority, however, have not quantified this. This is certainly worth evaluating, but we will not do that here. We do need to take into account the cost of disposing wasted material. Disposal costs vary among materials and PLANTS & PROCESSES
Sustainable EOY 2009