Let’s get to the point!
When that embroidery machine arrived at your door and the tech started it up for the first time, you probably stood there and marveled at all the engineering and technology that must have gone into the precise timing involved in creating stitches at such high speeds. The thing that amazes me is that one of its primary functions that it makes it run so smoothly is that with each revolution the machine makes, that little needle which carries the top thread needs to precisely interact with the rotary hook on the bobbin casing to create a perfect loop as the two pass each other. (fig.1) The truly amazing thing is that this happens while the machine is running at speeds of 700 to 1200 stitches per minute.
If you take the time to look closely at a needle you soon realize that and the incredible amount of engineering has gone into what soon becomes an item that besides bobbins is changed most frequently and disposed of. The needle itself is made up of many components that are shown in the following diagram. (fig.2) You’ll notice that the front and the back of the needle are very different and need to be placed in the machine with a fair bit of care and accuracy. If you’re placing a new needle on the machine and you don’t line up the “eye” of the needle so it’s perfectly straight, you will change the distance of where the “scarf” (back of the needle) meets the rotary hook and it will greatly affect the performance of the machine. I know this should fall into the “common sense” category, but I can’t tell you how many times when I was running contract embroidery, that my seemingly experienced operators would make this mistake and then wonder why that head wasn’t embroidering well. Another simple mistake I saw repeatedly was that the “butt of the shank” wasn’t pushed all the way up to the machine, which obviously again changes the distance of the “scarf and hook timing.”
What does it all mean?
If we get right down to the basics, the smaller the needle the more detailed the design with less penetration to the fabric causing weakening. The larger the needle the heavier/denser the fabric, producing larger holes. Thinner thread = smaller needle, thicker thread = larger needle… Pretty easy, right? Needles come in sizes ranging from 60/8 to 110/18, the greater the number the larger the needle, with 75/11 or 80/12 usually being the most standard size. Looking at all the codes and system numbers for needles can quickly become confusing. The basic premise is that the numbers refer to the length of the needle, the eye size and location and the eye to tip distance. Shown is an example of the dimension and shape of a DbxK5 needle. (fig. 3) The best rule of thumb is to ask your machine manufacturer which is the best needle to use for most of the general applications on your machine.
I ran a contract embroidery facility for over 15 years with over 135 heads, 99 percent of the time we used a 75/11 sharp point needle. Changing needles for that “difficult” job once in a blue moon was necessary, but I never went overboard, trying not to cause a great deal of confusion and unneeded down time in production. For the most part, we wouldn’t even change our needles if we were running on leather, I would rather make sure the design was modified at the digitizing stage, creating a file with less underlay and density before it got to production. Time is money, and if you’re changing needles for 3-4 colors on 24 heads, that equates to excessive down time! If you are a shop that uses varying thread sizes you’ll probably want to try and use a needle with a larger “eye” size to accommodate them, but in my experience keeping it as simple as possible is a much better way to go.
What needle should I use?
At this point I’m sure I have a lot of people adamantly disagreeing with me! Changing your needles for varying applications is the way it should be done, but it will give you a lot more to consider. The first thing a lot of you must have thought was “he used sharp point needle for everything? Aren’t they just supposed to be used on woven materials?” If we get technical, using ball point or universal needles is much better for certain applications and absolutely necessary for others. A ball point needle will push aside the fabric rather than puncture through it and will prevent damage on knit goods if you do very intricate work on fine satins, let’s say geared to the lingerie industry you’ll definitely need to switch to ballpoint. Then within the “ball point” family you can choose light ballpoint, medium ballpoint, special ball point and heavy ballpoint. Varying for fabrics from lightweight knits and satins to extremely bulky sweaters and everything in between.
If you are trying to run your designs on leather without modifying them you’ll pAllrobably need to switch to a “narrow wedge point” needle. The idea behind this needle is that as it perforates the leather it leaves enough distance between the stitches in the embroidery to maintain the strength of the leather. You might actually be able to punch out the design after embroidering it you don’t. (fig.4)
If you’re having trouble running metallic threads, switching to a needle with a larger eye or a needle particularly designed with an eye shaped like a rectangle will aid the passage of the thread through the needle’s eye. Again, I cheated and kept my thread saturated in silicone rather than going through the process of changing needles.
Various manufacturers offer needles with different coatings that make them unique. Single-head machines will run considerably faster than their multi-head counter parts. A machine running at 1200 stitches per minute will create heat and friction that can cause synthetic threads to break as well as melt holes through some types of synthetic fabrics. Standard needles are chromium plated and as they heat up synthetic material may stick to the needle. Teflon TM coated and “Cool-Sew” finishes on these needles helps alleviate the sticking and heat-buildup problems.
Needles with a titanium-nitrate ceramic finish makes them more wear-resistant extending the life of the needle 3-5 times longer and can also be helpful when trying to embroider through very tough fabrics. They not only maintain their needlepoints longer but also maintain overall strength with reduced deflection at high speeds.
It’s said that the average needle life is approximately 2 million stitches. If we try and break it down to just how long that is it might look something like this.
Speed 650 stitches/m
@ 100% run time= 312,000 stitches/day
@ 80% run time= 265,200 stitches/day
2,000,000 / 265,200 = 7.5 days
Now that’s a nice little equation on paper, but try and keep track of it if you have an 18-head machine with 9 needles…that’s 162 needles to keep track of! In production, we had a simpler strategy, if it wasn’t broke don’t fix it! An experienced operator can tell by the visual look of the embroidery and the machines performance if a needle life has expired.
Skipped stitches can generally occur if the needle groove and size of the eye are not appropriate for the threads size or characteristics. Improper rotary hook timing can also cause this effect. It’s much easier for the operator to first problem solve by checking the needle, than it is to right away start messing with the rotary hook timing. (fig.5)
Play it Smart!
Above all else, maintain a healthy respect for that little piece of metal. Operators tend to get a little cocky as time passes by…thinking their ability to clean stray threads while the machine is running is a measure of their experience. Over the years, I’ve taken my fair share of employees to the emergency room, I used to try and lighten things up by saying “your not a true embroiderer till you’ve gotten a needle through your finger”. I’ve had it happen twice, so I don’t know if that make me a really good embroiderer or just stupid! The second time it happened I hit bone, did you know that the needles shatter into many pieces when that happens? Funny thing is it happened the day my eldest son was born. I was downstairs having my finger dissected while mom was upstairs in labor, meanwhile the staff is keeping us both updated with each others progress. I did make it to the delivery room with time to spare and it’s not hard to forget the last time I put a needle through my finger.