Manual or automatic, it really doesn’t matter–all garment-printing presses need regular maintenance in order to operate properly. Proper operation means more than just running; it also means printing in register consistently, from platen to platen and job to job.
Most shops do not have a structured maintenance program in place to make sure that every press operates at peak efficiency. In fact, it is an unfortunate reality that most shops don’t do anything to their presses until something breaks or the operator cannot get a proper print.
The old adage “If it ain’t broke, don’t fix it” does not apply in the real world of business. How would you feel if that were the approach that airlines took with aircraft maintenance? Although a broken press is not as life-critical as a broken airplane, it is critical to the operation of your business.
Think about what breakdowns cost you in terms of downtime. Not only do you have people standing around and jobs not getting done, stoppages from equipment failure force you to back up future orders and restrict your ability to accept new business. Just consider the following analysis:
Cost of three hours of downtime due to automatic-press breakdown–
Labor: 2 @ $10/hr plus 2 @ $7/hr plus benefits for all = $132.60
Prints lost: 500/hr @$0.40/piece = $600.00
Total loss: $732.60
You might argue that you can always send people home and print the shirts when the machine is fixed, but both of these solutions ring hollow. A better way to put it may be that the $732.60 is opportunity lost, because the clock did not stop while you waited for the machine to be fixed. You cannot recoup that time. Yes, you can work overtime to make up, or you can push jobs back, but when you do, that costs too.
Invariably, equipment goes down at the time when you can least afford it–when a huge order is due. And while you can’t prevent all equipment breakdowns or parts failures, proper maintenance can minimize these issues. Proper preventative maintenance is not expensive. If anything, you save enough money in reduced downtime and rejects to cover the up-front cost of maintenance.
Who’s responsible for maintenance
If your shop is relatively small, you probably do not have a full-time, or even part-time, maintenance person. If this is the case, then your press operators need to take personal responsibility for maintenance. Maintenance tasks are not difficult to learn or perform, and they don’t take much time if done on a regular basis. The benefit of putting the press operator in charge of maintenance is that nobody better knows the idiosyncrasies of the press.
Larger shops that can afford a maintenance person rely on that individual to keep maintenance up to standards. Most successful large shops discover the hard way that a full-time maintenance person and a regular maintenance program pay for themselves very quickly.
Whichever approach you can afford, the maintenance plan is useless unless if not carried out on a regular and consistent basis. The best way to monitor the procedure is to create a machine-maintenance log. The log functions as a checklist to make sure that nothing is missed and as a management tool to ensure compliance. A sample log is shown in Figure 1.
The log does not take a lot of time to administer, but it does help to instill a sense of importance in the process. Operators who have to take the few minutes to fill in the form tend to take pride in its accuracy. However, there is a significant danger in the use of these logs: If the discrepancies noted in the logs are not remedied in a timely manner, the logs become just another waste of time. Any problems must be brought to a supervisor’s attention immediately, and a solution must be worked out as quickly as possible.
|Figure 1 Maintenance Log|
|Compressor oil level|
check mark = maintenance performed satisfactorily minus symbol = service or repair required
Note: All minus signs must be brought to the supervisor’s attention immediately. Supervisors should use the back of this form to log repair schedules and remedies.
Where to start
The best place to start a maintenance program is with the operator’s manuals that came with the machines you have. If a machine was purchased used, or if you cannot find the manuals, try to get a replacement set from the original manufacturer. If the company is no longer around, or if the manuals are simply unavailable, you can develop a maintenance plan by reviewing the manual from a similar machine.
When you just cannot obtain a manual that seems to relate, then you’ll have to start from scratch. Fortunately, screen-printing presses are not terribly complex. Most of the steps you should take are really just matters of common sense. Unfortunately, most printers think that maintenance is nothing more than oil and grease. Proper press maintenance actually includes a complete program of cleanliness, lubrication, alignment, and testing.
Keep it clean
Some shops don’t adhere to the “If it ain’t broke…” theory. These businesses are easy to spot because of one peculiar characteristic–they are clean! Textile screen-printing shops are inherently filthy, with fabric lint, adhesives, and inks all over the place. Real effort is required to keep a shop, and even more importantly, a press, clean. Those shops that make the effort to keep their operations neat and tidy tend to be well-run, low-downtime, shops.
Keeping a press clean is not very difficult if you follow a daily maintenance routine. You should quickly wipe down surfaces, remove ink when it gets on the machine, and clean the area around the press after each job–or at least at the end of each shift.
When I introduced this philosophy into my own shop, I was initially met with a high level of resistance. Most of my staff said maintenance would take too long and that they would have to start cleaning a half hour before quitting time in order to get it all done. The reality of the situation was much different. Yes, the very first cleanup took several hours. But once we had everything clean, we only had to spend minutes each day to keep it up. We also learned some good tricks along the way that made the job easier, and we started a friendly competition among the press operators to see who could keep their machine looking and running the best.
One of the most effective tricks for keeping printing equipment clean is to keep a protective coating on the press. Doing so makes it easy to wipe off lint and adhesive residue. In the old days, cleaning up with mineral spirits assured that a little oily film would remain to keep the lint and adhesive combination from getting a firm hold. The best tool today seems to be to light oil, such as WD-40, that imparts a similar film but emits fewer volatile organic compounds than mineral spirits. Other cleaners, including some citrus-based products, may also impart a film to protect the press’s surface. The most important aspect of any of these cleaning methods is that they must be done on a consistent basis in order to maintain the film. Even a film produced by a high-quality cleaner won’t do you much good if you wait six months before cleaning the press again.
Another simple but effective trick is to shield the press stand and floor around the loading/unloading area with cardboard, as shown in Figure 2. This minimizes the amount of platen adhesive overspray that reaches the press surface and makes cleanup simple.
Please keep in mind that no matter what cleaning method you use, you have to exercise care when using or applying any chemicals. Please review the Material Safety Data Sheets of the chemicals you use for information about correct personal protection, flammability, and other safety issues.
Once the presses are clean, lubricating becomes much easier because you can actually see if press components need more oil or grease. Most carousel presses have a center shaft upon which the platen carousel rides. The grease used to lubricate this shaft is clearly visible (Figure 3). Additionally, all presses, regardless of type, use a pin or bearing system to align the platens with the printheads. The spots where these surfaces meet are lubrication points that require continuous attention (Figure 4).
Automatic presses also use compressed-air systems, at least to a small degree. Compressed-air systems contain an oiler that provides constant lubrication to the valves and cylinders in the pneumatic system. This oil system draws from a reservoir that must be maintained to make sure the system does not run out. On some machines, the oil reservoir is positioned in a conspicuous location where it cannot be ignored.
Lubrication procedures are outlined in equipment-operation manuals. Most of these documents indicate that grease should be applied at least weekly–twice weekly for heavy use–and specify that oil levels should be checked daily.
I have asked many shop owners the following simple question: “When was the last time you checked the alignment on this press?” The answer is almost always the same: “When it was installed.” Even presses that are working well, including ones that are designed to stay in alignment even when they are run hard, will fall out of alignment. Constant adjustments to off-contact, as well as squeegee and floodbar adjustments, screen changes, platen changes, and even the continuous use of a flash-cure unit, will slowly, but surely, push a press out of alignment.
Plan on spending several hours tackling your first press alignment. If you align your presses regularly after that, you’ll spend less and less time on the task. I spent five hours on my first press alignment. The machine was quite out of configuration, but some of those five hours went to mastering the alignment process. The second time only took one hour, and after that, the time spent dropped to about 30 minutes every two weeks.
The time saved by just that first alignment was far greater than what I lost. Job setups became easier, jobs ran faster, and error rates dropped exponentially. You’d be amazed by how much time is lost when one platen is out of alignment with the rest. The press operators constantly try to adjust squeegee/flood pressures and speeds to compensate for the one platen, and they end up with inconsistent prints no matter what. More importantly, they end up with a slower production rate than if everything were aligned properly in the first place.
When you decide to align a press, make the press’s first printhead your starting point. Insert a stretched, blank screen, secure the screen into the normal print position, then place a level on the edge of the screen frame and check to make sure it is true. If the screen is not level, make the appropriate mechanical adjustments to bring the printhead and screen assembly to the correct plane.
The next step is to compare the position of each of the platens to the first printhead. Each platen should be raised in sequence (or the head lowered to each platen, if your press is of that type) until you can compare the platen to the screen in the first head. Use an off-contact gauge to check position of each platen relative to the screen. If you do not have an off-contact gauge, I recommend you get one of these modestly priced devices for your shop. Do not make any adjustments to the platens yet. You only need to determine how far off the platens are in comparison to the first head. Record the numbers on a sheet of paper so that you can compare the results once you have checked every platen.
If all of the platens are in an off-contact (versus on contact) position from the first head, you can proceed to adjust each of them to that head at your normal off-contact position. Start with the first platen and designate it as platen #1. Mark this platen as #1 and always use it as your registration and off-contact reference platen.
After you are satisfied with the first platen’s setup, double-check it by using your level to see if it is true. The platen should be level front to back and side to side. If it is not, back up and recheck your first head and readjust the platen until it is both at proper off-contact and level. Now you are ready to repeat the process with each platen. Compare them to the first head and double check them with your level.
Once the platens are done, it’s time to do the rest of the heads by using your clean screen from head #1 in each head consecutively and comparing the heads to platen #1. Remember, now you are adjusting the off-contact settings on the head. Do not make the mistake of moving the platens again, or you will have to start all over. Use your level to double-check your results and verify that each screen is true, both front-to-back and side-to-side.
As I mentioned earlier, the first press alignment is time consuming, but once the routine is established, it goes very quickly. High-volume shops should check their presses weekly, while smaller shops can comfortably check press alignment monthly.
Testing takes many forms. You can test a machine by cycling it and making sure all of the mechanical parts function, or you can actually create a test screen and make sure the press prints like it should. This is not as fun as it may seem.
After you have aligned a press, especially the first time, take a single, high-resolution screen and put it in head #1. Using minimal off-contact and black ink, print the image on a piece of test fabric on every platen. Using minimal pressure is an easy way to expose any difference in platen-to-screen distances. If everything is aligned correctly, all the prints will be identical. If not, at least you will know which platens need more attention.
Testing also should include a check of the safety features of automatic presses. Inoperative safety devices can cost you. Some companies have gone out of business because press-safety devices did not work properly. The resulting lawsuits from injured employees bankrupted the firms. Test the safety devices, and make any necessary repairs immediately.
All of the aspects of maintenance that I have discussed also apply to manual equipment. No, you do not have pneumatic cylinders or electric motors, but you do have springs, clamps, and registration bearings or posts. Cleanliness, attention to lubrication, and alignment also will keep a manual press operating at optimum efficiency.
Maintaining a parts inventory
One of the biggest problems I see in shops that I visit is a lack of spare parts. Anyone who has owned a press for a while knows which parts are likely to fail on a regular basis. Keeping basic items in stock, such as proximity switches, seals, nuts, bolts, springs, handles, switches, and even valves, can save a tremendous amount of time in the event of a failure.
You only need to keep larger, more expensive items on hand if you can’t afford any lost time. However, it is probably not cost effective for a small- or medium-sized shop to keep expensive parts or sub-systems in stock, unless those components fail often. In the modern world, with overnight freight, the downtime can be kept to a minimum without a massive investment. In the end, you have to judge what is important to keep handy based on its cost and failure rate. Not having the basic, inexpensive parts on hand for a quick and easy fix is bad management.
Murphy and the machine
Breakdowns always seem to happen when the job on the press is the most important one you’ve worked on in months and when the deadline is extremely tight. But by employing regular routines and standard practices for maintenance, you’ll be able to keep you presses running and improve the productivity and profitability of your business.
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