Go back to basics if you want to move up a level, says Marshall Atkinson, in the first of his two-part guide to mastering the art of screen-making
What’s the biggest problem facing shops that screen print apparel? Here’s a clue: this problem gets ignored most of the time and blame is probably assigned to something else when your print isn’t looking like it should. Is it the ink? Maybe the press? The garments you use?
It’s none of the above. The biggest problem in your shop and in the apparel decorating industry is screens. You can’t have great screen printing without great screens, and yet they are often overlooked in the process for some reason.
Every day people stand around their presses trying unsuccessfully to dial in a print, trying to figure out why it looks so bad. They adjust the pressure, change the squeegee, play with the ink and the off-contact. They will double-, or worse, triple-stroke a print to get better opacity. Some shop production managers have a ‘secret recipe’ for the ink to improve a print. Curable reducer, chino base or extender is added for smoothness, while sometimes even a percentage of puff ink is added for opacity.
It is all a gigantic waste of time. Band-aids all.
Remember this, my friends: the keystone to profitable screen printing production is your ability to create a perfect, production-ready screen on a consistent basis. It‘s how the high performing shops put distance between themselves and the competition.
Using the right tools
Time, then, to take a closer look at why print shops are failing to produce perfect screens. Often, it’s because they’re not using the right tools. Shops tend to skimp on the screen room and opt for flashier things instead, like a better press. That’s where the investment goes: when we can’t get enough of our orders printed and out the door on time, maybe adding another press will help.
Except that nobody stopped to look at the daily downtime or amount of impressions printed each day by the presses already on the floor. How much of that downtime can be attributed to a problem with your screens? What percentage of the inefficiency in production is caused by having to double-stroke a print to get decent coverage? For many (most?) shops, quite a bit! They just don’t know that because nobody is tracking and analysing the information.
Here’s a simple tip: less downtime equals more production.
Study the numbers
To show you the value of a perfect screen let’s look at some numbers. This is an example, and I’m sure your shop metrics will be different.
Example shop – Week 1
Automatic press – Sets up ten print locations per day on average. That’s 50 for the week. Average colour count for each order is three screens. It takes about nine minutes per screen to set up, but nobody is really checking. Some jobs take longer as there are registration problems with the screens. Order size is somewhere between 50 and 144 pieces, so for ease we’ll call the average order size 100. The press prints at an average of 400 impressions per hour.
Manual press – Sets up eight print locations per day on average. That’s 40 per week. Average colour count for each order is two screens. It takes about ten minutes per screen to set up as the printer is still fairly new; he often needs help to get the registration right too. The manual handles orders less than 48 pieces, but the average order size is about 35. The press prints at an average of 65 impressions per hour.
The production team works eight hours per day, but with breaks and lunch, they are available to print seven hours per day. 7 x 60 = 420 minutes.
- 10 locations x 3 screens x 9 minutes per screen = 270 minutes for screen set-up per day (4.5 hours)
- 10 locations x 100 piece quantity/ 6.66 impressions per minute (400/60) = 150 minutes for printing (2.5 hours)
- 150 minutes printing x 100/420 = 36% uptime printing (64% downtime) for the day. Only 36% of the day is spent actually printing shirts
- Total average impressions = 1,000 per day or 5,000 per week
- 8 locations x 2 screens x 10 minutes per screen = 160 minutes for screen set-up per day (2.7 hours)
- locations x 35 piece quantity/1.08 impressions per minute (65/60) = 259 minutes of printing (4.3 hours)
- 259 minutes printing x 100/420 = 62% uptime printing (38% downtime) for the day. Better than the auto, but still only 62%
- Total average impressions = 240 per day or 1,200 per week
Remember, your shop is only making money when you are decorating a shirt.
So, for downtime – the time spent not printing a shirt – would 64% for an auto or 38% for a manual be acceptable in your shop? Probably not. So let’s fix that by tweaking just one thing: screen set-up time.
Let’s say the shop did an awesome amount of work digging into the challenges associated with its screens, and with improvements and some training, it got set-up times down to an average of five minutes a screen.
Shop floor maths – Week 2
- 10 locations x 3 screens x 5 minutes per screen = 150 minutes for screen set up per day
- This adds 2 hours to the production day (270 – 150 = 120 minutes)
- 150 minutes print time before + 120 minutes of new availability = 270 minutes for printing daily
- 400 per hour impressions x 2 hours = 800 extra impressions available per day
- Total average impressions = 1,800 per day or 9,000 per week
- Extra 4,000 impressions per week x 52 weeks = 208,000 extra impressions per year
- 8 locations x 2 screens x 5 minutes per screen = 80 minutes for screen set-up per day
- This just added 1.3 hours to the production day (160 – 80 = 80 minutes)
- 259 minutes print time before + 80 minutes of new availability = 339 minutes for printing daily
- 65 per hour impressions x 1.3 hours = 85 extra impressions available per day
- Total average impressions = 367 per day or 1,835 per week
- Extra 425 impressions per week x 52 weeks = 22,100 extra impressions per year
These are example averages and real production numbers are more complicated. They do, however, show how reducing your screen set-up time can get you an extra 230,100 impressions per year without buying any new press equipment.
Push for lower set-up times
If you have any sort of volume in sales and have a packed schedule, pushing for lower set-up times of under five minutes per screen on average is how you justify that computer-to-screen (CTS) system, registration system or other capital expenditure in the screen room.
A CTS system works great as all of the screens for an order will be perfectly registered to each other when they are imaged. Using it in conjunction with a registration system means they simply lock into place with minimal effort.
Do you know your average screen set-up time? Or, like a lot of shops, do you just guess? Telling yourself, “We do okay”, but not measuring this step is delusional management.
How do you do that?
For starters, let’s look at things from a general perspective in the screen room. There are five main steps in creating a functional screen:
- Emulsion coating
- Imaging and exposing
Without craftsmanship in these processes, things will fail in production and you’ll spend a lot of unnecessary time adding some sort of band-aid to the problem.
This is the number one factor for screen success. Why? Think about it. What is easier to shear ink through: a screen that acts like a trampoline or one like a hard sheet of glass? The higher the tension of your screen, the less effort (pressure) will be required to pass the ink through the screen and onto the surface of the shirt.
Are you measuring screen tensions in your shop? Most shops don’t. Sure, they might actually own a tension meter. But it doesn’t come out of that hard plastic very often. Just how thick is that lint layer on yours?
Screen tension is a critical component of good quality screen printing. As such, you need to create screen tension standards for your shop and use them. They don’t have to be anything super elaborate either.
Screen tension recommendations
- Don’t use anything under 18 N/cm – that’s bottom line standard
- 18 N/cm – 20 N/cm is only good for one-colour orders
- Above 20 N/cm works for multi-colour orders
- Keep all screens for multi-colour orders within 2 N/cm of each other
- The higher the tension the better
- If a “just good-enough” print is okay, then “just good enough” tension will work. If you want fantastic, awardwinning prints, then you need to ratchet up the tension level. I’d use Newman roller-frames and higher mesh counts too
- Nobody on this earth has magic fingers. You can not thump a screen like a watermelon and gauge accurate tension. Professionals use the correct tool. Buy (and use) a tension meter.
Band-aids that point toward tension problems
- You’re double-stroking instead of using one pass. Every time you doublestroke, you double the cost of the ink for that screen and add to the total production time for the order. This is inefficient. Doesn’t it bother you that it takes twice as long to print? It should.
- You use two underbase screens for coverage. What could be driving that?
- You’re experiencing registration issues on-press, but the art lines up perfectly on the film or on the computer. This shows up with the white underbase peaking out from a colour and not being able to move the screen around enough to solve the problem. And it’s a double whammy if the solution from the printer is to use more pressure.
- Your prints are rough. If your final print looks like lumpy cake icing, this is a tension issue. However, most shops diagnose this as an ink issue. Anytime you need to heat press your print to make it smooth, you might want to dive into some tension research instead.
- You need lots of pressure to print. If your squeegee is doubled-over like a capital ‘L’, that’s not right. The goal is to shear the ink through the screen and have it kiss the top surface of the substrate. With a decent tensioned screen, the squeegee doesn’t require much pressure to clear the ink. If you can see your print on your platen board, you are driving the ink through the shirt fabric and onto the board. This ‘hammer pounding the nail’ technique affects opacity and usually is why printers double-stroke or use a second underbase screen.
Follow the link for part two, where I‘ll examine the remaining steps that will help your shop create the right screen for the job, time after time.
Marshall Atkinson is a leading production and efficiency expert for the decorated apparel industry, and the owner of Atkinson Consulting, LLC. Marshall focuses on operational efficiency, continuous improvement and workflow strategy, business planning, employee motivation, management and sustainability. He is a frequent trade show speaker, article and blog author, and is the host of InkSoft’s The Big Idea podcast.