Update for our team July 12, 2021: At Concor we know screws and barrels. We are technical experts in this field, and for those who share our passion for perfectly-designed and built components, here is some reading on TIR. We thank those of our customers and representatives who read this captivating and important material, and then put it to good use.
At the center of this discussion is the screw. Made to the S.P.I. (Society of Plastics Industry) standards, the screw must be straight (+/-.001). The drive, shank, body (minor diameter), tip locating diameter and tip threads must all run true to the centerline. The proper machining and straightening insures a stable and consistent processing of material as it travels down the flight path. For the discussion that follows it will be assumed that the screw is straight, the flights are to the proper size and the barrel inside diameter is sized to its proper size and clearance. When a new screw is installed in a new barrel, it is assumed the barrel I.D. runs true to the centerline. How can you tell if it is? A bore gage will only tell you the I.D. size. The plastics industry refers to the measurement of straightness of the bore with the term T.I.R. (Total Indicator Runout). The S.P.I. standard for a barrel 1-3" bore dia. with an L/D ratio of 24/1 or less should have a maximum T.I.R. of .008. If the barrel is > 24/1 the T.I.R. should have a maximum T.I.R. of .010. In other words, how far off the centerline can the I.D. be and still be "acceptable". In theory, the straighter or true the barrel I.D. runs, the better the screw will function as it is injected forward and as it rotates to its fill position. Ideally, the screw should be straight and the barrel bore run true as well. Again, we are talking about T.I.R. (straightness) and not size. What happens if a barrel has a T.I.R. of .008 and has a straight screw installed that has .004 clearance? The flights will contact the bore at the point where max. runout occurs and at discharge end (see picture). Because the screw has some flexibility, it will usually slide in (you may notice a slight drag as it flexes slightly), but the contact of the screw flights with the bore is asking for problems. Premature wear, broken screws and processing issues can easily result. One important thing to note is that the outside dia. may run true. It's how the I.D. runs that is critical, see picture. We measure the T.I.R. with an actual indicator. Some manufacturers use a test bar to determine bore straightness. If the bar slides through the barrel, and doesn't hit any "kinks", the bore "seems" to be straight. We want a true measurement, so we use an indicator. Here is how we check T.I.R.: 1. Set up barrel in engine lathe and indicate in the outside diameter of the barrel. 2. We use an indicating extension, (a long shaft with a dial indicator attached to the end), mounted in the lathe tool holder. Insert shaft into the I.D. of the barrel. 3. Turn on the lathe at a low R.P.M. and bring the contact point of the indicator in contact with the I.D. surface. 4. Now observe the needle of the indicator. Any movement of the indicator needle reflects the T.I.R. of the I.D. of the barrel. 5. Gradually move the indicator shaft down the bore, stopping periodically to check the runout. Repeat this process until the entire length is inspected. At Concor, we strive for a T.I.R of .002 on our tool steel lined barrels (D2, 10V, etc.). The truer the I.D. runs, the better the process for our customers.
We are leading experts in designing, manufacturing, and rebuilding feed-screws, barrels, tips, and end-caps for injection molding and extrusion machines. Our customers across North America and the world, include large and small operators, along with multinational OEMs. Challenging mixing requirements, high-wear applications, upsizing, downsizing, high volume production, small-volume runs, micro precision requirements; we have done it all.
"AT CONCOR, YOU WILL WORK WITH A WONDERFUL TEAM OF PEOPLE THAT EXPERTLY DESIGN AND MANUFACTURE SCREWS, BARRELS AND VALVES THAT ARE VITAL TO YOUR PARTICULAR INJECTION MOLDING OR EXTRUSION PROCESS."
-BILL TALBOT, PRESIDENT
-BILL TALBOT, PRESIDENT
Feed Screws for Injection Molding and Extrusion
Barrels for Injection Molding and Extrusion
Tips (Non Return Valves) for Injection Molding Screws
End Caps for Injection Molding and Extrusion Barrels
Save money and go green at the same time! Please rebuild your screws and barrels instead of throwing them away! Contact us and learn more.
New Service Offering: Concor has been rebuilding complex screws and mixing sections for decades. We are happy to announce that Concor now offers rebuilding services for TWIN SCREWS, contact us to learn more.
Twin conical screws rebuilt by Concor Tool and Machine
CONCOR NEWS:
- April 2021: Concor is pleased to announce the appointment of Paragon Machinery Inc. as representative for New Jersey, Delaware, Maryland, Virginia, and Eastern PA. Paragon brings a wealth of knowledge and excellent local support to our customers in this region. Welcome aboard Paragon! Contact info: Eric Henderson 443-502-0088 eric@paragonmachinery.net, John Gudonis 717-745-5005 john@paragonmachinery.net
- 2020: Concor was deemed an essential business due to all our customers in critical industries including medical equipment manufacturing, infrastructure and energy/electrical components, food supply machinery, and the automotive and aviation industries.
Industries Served: Our customers are primarily engaged in injection molding and extrusion in the industries noted below. These products impact our lives in a positive way every day. The products made by our customers can be found every day in the following categories:
- Medical
- Electronic devices
- Automotive
- Aviation
- Agriculture and irrigation systems
- Construction
- Industrial products
- Athletic and sporting goods
- Consumer goods
- Food and Beverage
- Animal and pet food and product manufacturing
- Medical
- Electronic devices
- Automotive
- Aviation
- Agriculture and irrigation systems
- Construction
- Industrial products
- Athletic and sporting goods
- Consumer goods
- Food and Beverage
- Animal and pet food and product manufacturing
