Impressions - January 2011 - (Page 54)

EMBROIDERY >> HANDS ON Production By EMBROIDERYFrank Gawronski, HANDS ON Contributing Writer ITAL DECORATING >> HANDS ON CREEN PRINTING >> HANDS ON TECH TIPS HANDS ON How to Determine a True Thread Break >> DIGITAL DECORATING HANDS ON SCREEN PRINTING HANDS ON TECH TIPS HANDS ON Minimize production interruptions by knowing the difference between thread breaks, thread pull-outs and false thread breaks. Shown here is an example of an older style check spring that doubles as an upper thread sensor. When the upper thread breaks, the check spring grounds itself, thus stopping the machine and illuminating a red lamp that is normally unlit. Instead of using the check spring as a switch, many machines now meter the flow of the thread with optical encoder thread detectors that read both the upper thread and bobbin thread. Operating a computerized embroidery machine can be a very rewarding experience and career. Making a design come to life one color at a time is a mesmerizing mirage to the novice and signals the closure of a work order to others. No matter how you look at it, converting a “blank” item into a “finished,” marketable garment generates a unique sense of fulfillment. Even occasional interruptions, such as thread breaks, don’t seem to dampen that spirit. But when the interruptions reach a level that threatens the reservoir of good will found in each of us, that euphoria often changes to frustration — or worse. By its nature — and the complexity of the process — thread inevitably will break on occasion. This triggers a chain reaction that stops the embroidery machine and signals the operator with either a still or flashing red light over the embroidery head that is experiencing the problem. This is accepted as part of the operator’s job; simply re-thread the needle, back up to mend when necessary and continue with the sewout. Sometimes this thread break is just a fluke that indicates an adjustment may 54 Impressions >> January 2011 be necessary. Other times, it may not be a thread break at all. In this article, I’ll explore the machine signals, what they mean and the actions you can take to minimize these interruptions. THE SIGNALS Embroidery machine manufacturers have been using low-voltage electronic signaling to indicate thread breakage for several decades. Until recently, this was accomplished with a primitive switching system that used the check spring as the switch and a logic board, which was usually equipped with a red light and an on/off switch. When the upper thread breaks, the check spring grounds itself, thus stopping the machine and illuminating a red lamp that normally is unlit. As the technology developed, equipment makers began to add under-thread sensors, using more sophisticated strain gauges and electronic “eyes” to read the bobbin thread. When automatic thread trimmers were first developed, the quest for an under-thread sensing system was temporarily discontinued because they occupied the same physical space on the machine. Today, everything has changed. Instead of using the check spring as a switch, many machine manufacturers are metering the flow of the thread from the top of the machine with optical encoders to determine upper thread activity, as well as bobbin condition. With LED technology, the old “red light for thread break” notification method has changed to include a multilevel lighting scheme. With this new technology, no light means “head off,” a green light means “head operational,” a red light means “upper thread break,” and a flashing red light means “bobbin out.” In spite of this technology, the machine still does not know how to distinguish between a legitimate thread break, a thread pull-out and a false thread break. It is up to the operator to make this determination and take the appropriate corrective action. NOT ALL BREAKS ARE THE SAME As you can see, embroidery machines are programmed to illuminate a particular signal to the operator when a problem exists. For example, we assume an illuminated light means the thread has broken in production. However, in practice, there are

Table of Contents for the Digital Edition of Impressions - January 2011

Impressions - January 2011
First Impressions
ISS Show Focus
Winning Decorators Focus on Intricate Details
Special Report: The Cotton Crunch
T-Shirts Still an Industry Staple
Worthwhile Projects for the Slower Months
For Screen Printers Only
Use Sublimation to Create High-Value Photo Gifts
Online Directory
Business To Business
Ad Index

Impressions - January 2011