News Forwarded from Kunststoffe: The Danger of Cracks on Screws


When seeing a crack, first thing into mind is the danger of cracks on screws.  Have you experienced that?
Have you evaluated the danger of cracks on screws?
Would you take the danger of cracks on screws?

Have you ever received a hardfacing screw with cracks?
Have your screws ever got cracks after some time of using?
How do you evaluate the screw with cracks?


Reading from Kunststoffe is more enjoyable, you're seriously invited to check it out there.

“Hardy, we received your screws. Are you sure your people have done the inspection? Look at the crack, I think any people will see this clearly. How can we install such a screw on our machine? How fast can you get us a new screw? We need it now. Please let me know. ” As a screw manufacturer, EJS often receives such complaints.

Mistakes in the production?
When the first 125 hard-facing screw was ready for inspection, the employees at E.J.S Industry Co., LTD, Ningbo/China (EJS), noticed that there were cracks on the screws. How could that happen?

Was it caused by bad temperature control, or bad bimetallic alloy powder, or bad base steel, or process management? To find out why, a lot of tests were scheduled and a lot of labels were sticked on the product for later identification. After a lot of trial and error, EJS came to know WHO was the mother of cracks and their relationship.

Hardfacing screws are normally processed by a PTA welding machine. The energetic plasma arc has a high temperature more than 1000℃ to melt the alloy powder, which is to be welded into the flight one by one until it’s completely finished. During this process, the thermal expansion and cold contraction happens inevitably and repeatedly due to the big difference between 1000℃ and the ambient temperature(5℃ to 40℃).

Nothing to worry about
Since 2015, EJS had a special furnace to keep the hardfacing screws warm for certain hours after PTA welding, which do help us to reduce the numbers of cracks. Unfortunately some cracks are still there, big or small, more or less. Is there any way to get rid of them?
As a quality-oriented company, EJS tries everything to avoid cracks. However, it is not possible to completely exclude the possibility of cracks forming. The company consulted senior engineers, checked with experts, analyzed together with experienced production managers and sought advice from long-term customers in different countries. Finally EJS accepted the fact that cracks are inevitable for some alloys on big sizes, because no cracks means soft flights. There are some alloys which you cannot avoid micro cracks. They always exists.

Moreover EJS started to know that
When the cracks are intense, AND the flights always stay - it is acceptable.
When the cracks are long, AND the flights always stay - it is acceptable.
When the cracks are wide, AND the flights always stay - it is acceptable.
When the cracks are regular in one direction - it is acceptable.
If the crack causes the peal-off - it is NOT acceptable.

Using these simple questions, customers can check whether their screws are OK or not.
In case of doubt, the experienced EJS staff will be happy to help.


March 15, World Consumer Rights Day.

We EJS hope each consumer is well respected any time and any where, not only March 15.

As a screw barrel manufacturer, we EJS produce extruder screws and barrels, injection molding screws and barrels for OEM machine builders and end users.
Our entire company takes each customer seriously and handles their orders carefully, our customers have the rights to say NO to our products or even reject our products when there is an inferiority, they have their RIGHTS every day.

We believe that:

The most unhappy customers are our greatest source of learning.
How we think about your customers influences how we respond to them.
Quality in a service or product is not what we put into it. It is what the customer gets out of it.
Customers dont measure us on how hard we tried. They measure us on how hard we deliver.
Customers dont care about our solutions, they do care about their problems.

It's EJS' mission to take care of screws and barrels for your extrusion machines or injection molding machines, to evaluate the danger of cracks on screws, danger of cracks on screws| EJS news at Kunststoffe