Wednesday, December 31, 2008

Diamond grinding wheels

Industrial diamonds are not suitable for gemstones and are called bort, the diamond powder used in grinding wheels maybe synthetic or mined. Diamond powder is used for grinding wheels because of their hardness and heat conductivity; they quickly cut the hard steel with out generating a lot of heat.

Diamond grinding wheels use diamonds as an abrasive to grind extremely hard materials. Industrial diamonds are ground into a powder for use in grinding and polishing applications, this diamond powder is mixed with a resin bond to create a layer of diamonds and bonder on a metal core to sharpen hardened scissors, these scissors are heat treated and run from 54 to 62 HRC, hardness Rockwell C scale. Diamonds may be plated to a wheel core, they tend to be a course diamond, these type of wheels are not good when you have to remove a lot of metal, they are slower to cut and the blade gets to hot so that you can't touch it.

This picture shows sharpening hardend beauty shears blade on Diamond resin bond wheel. This wheel shown is 800 grit.

More Information on Diamonds:

Wednesday, December 10, 2008

Corrugating or serrating scissors and shears

Scissors blade with corrugations

Corrugations or serrations on a scissors are used to hold the material being cut in place. The teeth grip the slippery fabric, hair and keep fiberglass and kevlar from bunching up during cutting. Most cutting operations do not need these corrugations, but for certain applications they make the cutting job easier.

Kevlar, Spectra and fiberglass are difficult if not impossible to cut when it bunchs up. These teeth hold the material flat during cutting maintain a single layer that can be cut. These materials are very abrasive so the cutting edge breaks down quicker.

Sharpening your scissors with the Twice As Sharp® scissors sharpening system or other sharpener will remove these corrugations. You can usually sharpen the non-corrugated blade once or twice before the corrugated blade needs to be re-sharpened.

You have a couple of options when you need to sharpen the teeth off the corrugated blade. The most common is by using diamond corrugating files or a steel chequering file. The scissors blade needs be held tight at the correct angle in a vise like the Pana-Vise, and the file is used to create the teeth. Click here to learn more about the manual method of corrugating scissors.

Its fast and easy to corrugate with the new Wolff Corru-Gator

Another method to corrugate or serrate scissors is with the new Wolff Corru-Gator click here to learn about corrugating with the Corru-Gator.

Tuesday, December 9, 2008

Update on slide cutting:

Picture shows shears slide cutting fabric.

We have a customer that wanted to try a scissors with corrugations, small teeth on one blade. They called us to say that it was not working after getting this scissors.

We found out that they slide cut their fabric. Corrugations are put on a scissors to help keep the material from sliding out the blade while it is being cut. These teeth prevent the scissors from cutting the fabric during slide cutting.

Smooth slide cutting works best when both blades are honed.

More information on Slide Cutting

Wednesday, November 26, 2008

Slide Cutting

Picture shows shears slide cutting fabric.

What is slide cutting?

Slide cutting is one method used to cut fabric, instead of opening and closing the blades as someone normally does with scissors they use the blades of a scissors as two knife blades.

The operator opens the blades partially and then slides the blades cleanly through the product that is going to be cut. With fabric you may need to do a starter cut then you are able to slide through the material. When my parents owned a sewing center in Michigan they had a slot cut into their cutting tables and used this slot to guide the scissors as the slide cut the fabric for the customer. This works for best stiffer fabrics like cotton and vinyl.

Slide cutting is also used to remove flash when a product is removed from a mold. Flash is the excess plastic or rubber that is left behind at the parting lines or where the two molds come together. Scissors with curved blades are more popular for this application.

Scissors need to have both blades honed during the sharpening process to make it easier to slide cut. The operator also needs to change the point on the scissors the materials make contact with it or you get a heavy worn spot at this point on the scissors.

Contact us at Wolff if you have questions or need help with your slide cutting operations.

More information on Slide Cutting

Friday, October 17, 2008

Burn requirement requires use of Kevlar threads

July 2007 was a significant date for mattress manufacturers; you may think to yourself why this date has any significance? These manufacturers had to comply with the new “burn” regulations by this date or face fines and penalties. These companies had to completely redesign there manufacturing processes and materials to meet these new standards. To meet these standards all the manufacturers are using Kevlar® thread to prevent the seams from opening and allowing the fire to get past the fire barrier. Some manufactures are also using silica infused fabrics as part of this fire barrier.
Thread clips and scissors may have to be modified to cut these materials. Kevlar® is used in body armor to prevent shrapnel and bullets from wounding or killing the person wearing it. The Kevlar® is layered upon it self over and over again, as the object tries to penetrate the surface the multilayer’s bunch together and keep it from passing through. To cut this material you must keep the fabric spread out, if it bunches up the scissors will not be able to cut it. This is accomplished by putting corrugations on one or both blades, there are many weaves and weights of these materials and the scissors and thread clips need to be optimized for the materials you are using. Our in house R & D department gets samples of these materials and finds the correct angles and corrugations need for each of their materials.

This material is very abrasive and these scissors and snips must be sharpened frequently, using a high quality, harder scissors (HRC) your time between sharpening increases. We use the Twice as Sharp® scissors sharpening system to sharpen the scissors and then we use the "Corru-Gator" to put the corrugations back onto the blades. You can also manually put these corrugations or teeth back on the scissors blade using a diamond corrugating or steel checkering file.

The Kevlar® thread requires a higher quality thread snip to cut it, the edge of this thread snip needs to be modified to cut the specific thread that they are using, the snip may require corrugations like the scissors do. The new high strength fishing lines are made out of Specra®, they are light weight and stronger than the old mono-filament fishing line and therefore more difficult to cut.

On a recent site visit to a medical chair manufacturer’s R & D department I found that they are having problems cutting the Kevlar® threads, Kevlar® and Nomex® fibers that they have to use to meet the changing government regulations. We found that the KAI scissors cut this non-woven fabric without problems as long as the vapor barrier remains intact during the chairs construction. At times this vapor barrier will separate from the non-woven fibers and then they must use scissors that have been modified to cut the Kevlar® fibers.

Contact us here at Wolff if you need help cutting difficult materials like these.

Kevlar® and Nomex® is a registered trademark of Dupont.
Spectra® is a registered trademark of Honeywell.
Twice as Sharp® is a registered trademark of Wolff Industries, Inc.

Purpose of this Blog

As a manufacturer of scissors sharpening equipment, scissors and shears we have worked to find the best way's to cut a multitude of hard to cut materials. We have helped develop these solutions working with manufacturers over the past 25 years.

These materials may be something like Kevlar®, Spectra®, Nomex® and Fiberglass. Trimming rubber & plastic flash, materials for composites like pre-prag and carbon fibers. Proper tools and scissors maintenance are needed to process poultry and other food products.

I will write updates as our technicians and salespeople encounter cutting issues and develop solutions to these cutting problems. Please e-mail me David Wolff with any questions that you may have, I would also love to hear from you any unique solutions that you have developed and with your permission would post those that pertain to this blog.