Trim waste percentages:
In order to have a correct measurement and interpretation of the reports, it's recommended that your company defines what is a good, regular and bad trim waste percentage. There are plants that produce a great variety of different sizes and grades, seasonal products, etc., so it's convenient that every plant defines it's own trim percentages.
Of course any plant would like to have a trim percentage below 2%, but how can a plant get that number without affecting the corrugator productivity?
Another recommendation: If your plant manufactures large volumes of a single product, the trim waste percentage should not include these products or handle additional data without these high volume products because it helps reduce the percentage of waste, but the goal is implement strategies to reduce it rather than get a nice number.
There are several facts around the trim waste concept that we need to understand in order to define the strategies to reduce it.
" Not all that glitters is gold "
Low Trim waste it isn't always equal to Low Cost.
Before continuing, it is very important to clarify that there is a trap around the "low trim"; there are sometimes when a low trim is more expensive than a higher trim. Yes I know, it sounds illogical, but let's take a look at this example:
In the production by 3 outs, apparently, the waste trim is lower than by 5 outs, right? But look at the bottom, the total area is higher and, consequently, the cost is higher.
If your software doesn't have an option to calculate the total trim cost, it's important but very important to make the necessary adjustments to get this information, otherwise, you may be falling into this trap.
In addition to the trim cost, the production time is another factor, which in cases like this may be of greater impact than the cost of paper.
Opening more widths will reduce the trim waste cost but also will increase the inventory cost.
In the effort to reduce the trim waste cost, many companies open several widths assuming they will reduce it, and in fact it is, but only up to a certain number of widths.
By opening a new width, the plant automatically generates higher costs and greater difficulty in the operation and management of the inventory.
Here is an example with the same information but calculated to show three different scenarios: 5,7 and 10 widths respectively.
These are the general parameters:
Tonnage to purchase for the next 3 monthly periods: 8,186 net metric tons.
Cost per metric ton: $ 800 Dollars.
The initial inventory of each period was set to 25% of next month's consumption for each width
Less than 10 tonnes is rounded to 10 tonnes.
Tonnage exceeding 10 tonnes is rounded to the immediate multiple of 5, i.e. 17 => 20
There are other costs not quantified in this exercise like rounding up the quantities by grade to the minimum capacity of transport by truck or railroad, machine stops and waste of paper by more changes of width, etc.
In this exercise we can see that the cost of the inventory is greater than the increase of the trim waste cost. There are other costs that can hardly be quantified, such as the difficulties of organizing more widths, more time in locating rolls, more buttrolls, etc.
Now, this exercise is calculated to determine the optimal widths for the purchase of paper, however, there is a high probability of reducing the waste trim if your software to schedule the corrugator is a powerful tool to reduce waste with available inventory.