If you’re in the industrial manufacturing and packaging industry, you’ll appreciate the value of having quality cutting tools. Industrial machine knives are indispensable components in your system. They’re used to reduce material size while processing every conceivable product from paper to steel. While you may intricately know your business process involving machine knives, you likely don’t know much about the actual machine knife manufacturing process.Most manufacturing plant owners and operators focus on safe production with product volume being a key element for profitable success. Machine knives play a huge role in delivering dependable production. But knives rarely get much credit for their part. They’re barely noticed unless something goes wrong. As in every manufacturing system, there’s a distinct process to making top quality machine knives. York Saw and Knife Co. is America’s leading manufacturer of precision knives and saw blades. No matter what industry you’re in, we can supply your cutting tools and deliver you durable, accurate knives at affordable prices. Part of our customer service commitment is sharing information. Today, we’d like to explain how we manufacture machine knives.
Machine Knife Blade Metal Characteristics
Sharp knives are crucial in everything from food processing to manufacturing and packaging. There’s a wide variety of knife blade material, however, there are two main characteristics that go into keeping knives sharp. One is the blade material hardness. The other is blade material toughness.
Don’t be confused. These are two separate issues and need to balance to produce excellent machine knife blades that give long service. It’s the combination of hardness and toughness that builds great blades.
Hardness refers to the knife blade density. In the machine knife blade industry, we measure metal hardness on the Rockwell C scale. Generally, the higher the Rockwell C number is, the denser and therefore harder the material is. But just because a certain metal has a high Rockwell scale doesn’t mean the material is durable or tough. Many high-scale metals easily erode and quickly lose their edge.
Toughness refers to how well the knife blade resists erosion and abrasion. We measure a metal’s toughness by its Transverse Rupture Strength (TRS). In metal science, Young’s modulus of elasticity is the physical principle or guidance that scores a metal’s toughness. The higher a metal’s TRS score, the tougher it is.
You’d think that knife blades with high Rockwell C and TRS numbers would be ideal materials. Unfortunately, that’s not possible. TSR and Rockwell scores are inversely proportional. Physical properties dictate that harder metals tend to be brittle and damage easily. Softer metals can turn out to be incredibly tough as they exhibit elasticity that absorbs foreign forces.
Finding the right balance of metal hardness and toughness is what York Saw and Knife customers depend upon. We have a selection of proven blade metals and rely on those as backbones for our manufacturing process. Still, we often get customers shipping us their own machine knife blades to replicate or reproduce.
The first thing we do is analyze the metal and determine its characteristics to reverse engineer it. Then we follow a simple six-step process in manufacturing machine knives. We use this process regardless if we’re producing stock knives or building custom applications.
Here is how the York Saw and Knife Manufacturing Process Works:
Step 1: Send Samples
We first start with a machine knife blade sample or drawing. That’s usually provided by our customer who has existing machinery with specific knives. We’re asked to reproduce the knife’s configuration. Often, we’re also asked to improve its performance characteristics to make the replacement model harder or tougher.
We always recommend you call our sales engineers or converse with them by email. It’s helpful to attach digital photos or drawings of your blade. We’ll discuss your application, and try to solve your problem and provide a workable solution. We’ll also ask specific questions about your existing knife material type, the geometry of your blades and the types of products you’ll be cutting.
We’ll then request you ship us your blade or blades for testing. There’s no charge for testing at York Saw and Knife. It’s part of our extended customer service. Once we’ve looked at your knives, we’ll provide you a complimentary quote. From there, we’ll wait for you to authorize us to proceed with Step 2.
Step 2: Reverse Engineering the Knife
Reverse engineering is a fancy term for doing things backward. In a normal manufacturing process, a product starts life after engineers spent tremendous time doing research and development in designing and testing prototypes. This is long before the final product turns out.
When you ship us a machine knife to replicate, we’re now starting with a finished product and have to figure out how it was built. That’s engineering in reverse. We can see your configuration but have no idea what it’s made of until we do engineering tests.
First, we use an optical comparator to build a computerized model of your machine knife blade. This assesses the physical size, precise angles, and specifications like blade serrations and mounting pin-holes. We also assess any difficulties we might foresee when replicating an operational model.
Next, we use a Rockwell testing machine to determine how hard your blade is. We also assess your existing metal’s toughness. Then, we conduct a metallurgical analysis to find out your existing metal characteristics. This way, we’ll know if we can reproduce the blade with similar metal or if we should recommend changing to another alloy.
Finally, we do precise physical measurements. That involves a computerized press to load strain on the blade, measuring with digital calipers and using a precision micrometer similar to what’s in a machinist’s toolbox. Once we’ve reverse engineered and have a physical compilation of your blade along with steel attributes, we send this information to our Engineering/Estimation department. They’ll prepare you a detailed and firm quote for production. To learn more about reverse engineering, click here!
Step 3: Cutting and Heat Treating the Blade
All York Saw and Knife products begin with raw steel. We have a regular stock of proven metals that we know will properly perform against the materials you’re cutting. Our mainstay steel stock includes spring steel, carbon alloy steel, tool steel and high-speed steel. Although we rely on these proven metals, we’re capable of custom building you any form of machine knife profile.
Once you’ve approved shop drawings for your knife, we cut its profile from steel stock. We use two different cutting processes depending on the order. One is water-jet cutting where extremely high pressurized water slices through the metal stock. The other cutting method is done by laser or amplified light. Laser cutting is our preferred method, and we’ve invested in a Trumpf Laser 2025 machine for the most accurate cuts possible.
Once your knife if cut or profiled, we put it through a series of heat processes. This determines the final hardness and toughness of your blade. There’s a three-step process to hardening:
Hardening: Iron-based steel alloys get sent to a furnace with temperatures set at 1,750 degrees Fahrenheit. This is below the melting point but sufficient for letting metallurgical changes take place. The metal type determines how long the blade stays at this heat. Time is a critical factor in the hardening step, and it’s crucial for the blade to spend the exact period under heat.
Quenching: Once your blade has spent its precise time basking in the oven, it’s quickly removed and rapidly cooled. Usually, that’s by dropping it in water. This causes a molecular structure transformation. Again, time is a prime factor for successful quenching. Molecular changes continue until your blade reaches ambient or room temperature.
Annealing or Tempering: Once your knife blade reaches ambient temperature, it’ll be at its maximum hardness. That’s not necessarily the best for performance given the inverse relationship between hardness and toughness. The metallurgical experts at York Saw and Knife know the exact steel hardness they’re looking for. Now they temper or anneal the blade to lower its hardness for optimum performance. Your blade goes back to an oven at temperatures between 300 and 1,000 degrees Fahrenheit for four hours or more.
Step 4: Machine Finishing, Grinding and Sharpening
Once your machine knife is properly tempered, it’s ready for finishing, grinding and sharpening. This starts with flattening and tensioning that relieve built up stresses inside the blade. At York Saw and Knife, we use proven processes to destress and flatten your blade. Some involve sophisticated computer-aided machines. Others rely on the keen eye and skilled hands of our machinists.
If flatness is an issue with the blade being out-of-true, we use a Levelling and Tensioning machine. This device is designed specifically for the machine knife making industry. It helps our Anvil Room Technicians save labor and hours by automatically sensing out-of-true faults and correcting them.
Still, there’s no replacement for the human touch. Some knife profiles require special lighting examinations to find blade body inconsistencies. We use different weights and face-grind configurations such as the Dog and Twist approach. That might sound sophisticated, but often our machinists and technicians simply use special hammers to tap away problems.
Other truing steps include flattening blades with an auto-feed press, spinning them on an axle while checking trueness with a dial indicator and laying the blades on a flat table and visually examining them with a machinist’s straight edge. At this stage, workers use a precision hammer for corrections and alterations.
Finally, your new blade is finely ground for a sharp edge. We employ both automated and manual grinding and sharpening methods. Mechanical grinders put a rough edge on blades while final honing leaves the finished product with a razor’s edge. It’s the last knife-making stage before entering quality control.
Step 5: Final Quality Control Check
No matter how sophisticated our equipment is, we can’t depend on automation alone for quality control. Each of the previous process steps has its quality control parameter. However, every so often a flaw slips through. At York, flaws are not acceptable.
When you receive your York machine knives, you’re assured every blade passed a visual inspection. We look for obvious flaws and the not-so-obvious mistakes. Any blade not meeting the York quality control check is pulled from the line. Faulty blades are either reworked or discarded.
Part of our quality control process relies on experience. York Saw and Knife started manufacturing in 1906. That gives us well over 100 years of experience. We know how to manufacture top-quality machine knives and saw blades. As a result, our initial manufacturing processes are excellent, and we rarely have issues with our products. If so, they’re caught by sharp eyes and never leave the shop.
Step 6: Shipping and Using the Blade
Finished machine knives are precision products. They deserve to be treated as such. We take great pride in every blade we manufacture, and we’re determined to see it arriving at your door in pristine condition. As a York Saw and Knife customer, you wouldn’t have it any other way.
Our packaging department pays special attention to sharp edge protection. We package all our shipped products with extreme care and attention to detail. Once we protect the primary cutting edge, we ensure the blade is individually wrapped to avoid metal-to-metal contact when we ship multiple blades in one order.
Our shipping department makes sure there are no loose products in any order. We isolate all machine knives even if they’re mass-shipped to your facility. Our outer packaging materials are proven as reliable performers, and they protect your valuable blades on their way from our shop to yours.
Once you install and begin using your new York Saw and Knife blades, take time to look at your finished products. If you’re not satisfied for any reason, contact us immediately and we’ll rectify the situation. Problems with York knives are unlikely. We’ve built our reputation on quality and dependability.