Technology

Converting Design to Delivery

A process is the sequence and organization of all activities needed to convert material into products that were designed to meet customer demand. Then there is a final check or inspection to make sure that it meets standards for quality, quantity, lead time, or timing.

1. Blade Shaping

The shears are blanked out. Strips of steel are cut out in the form of a shears. The cheaper version of the “blanked” shears are then ground into shape so that it is difficult to sustain precision. We employ a “fine blanking” technique to shape the blade and punch screw holes. The process is capable of producing a sheet metal part with completely smooth edges. It needs no second machining and grinding. This means that not all blanked shears are cheap.

Blanking Process

Single Part

Single Part Transfer: A single part transfer is a method in which single parts are moved from station to station for blanking and metal forming. The relative dimension of shape and holes is in loose tolerance.

Single Stroke: Blanking and forming in one die stroke. The relative dimension of shape and holes is in tight tolerance.

Progressive

This is a forming process that utilizes a series of stamping stations to perform simultaneous operations on sheet metal. The final metal workpiece is developed as the strip of metal is processed through the stamping die. It’s low cost. However, the grain will be across the blades. This will reduce shearing force of blades and the blades may snap off.

Fine-Blanking

Compared with the fine-blanking, conventional stamping is found to have about 1/3 shearing edge and their shape is bowed whilst those produced by the fine-blanking are found to have 100% shearing edge, flat shape, and accurate dimensions. Furthermore, in applying the fine-blanking technology, the clearance between the punch and the die is much smaller.

Advantages

By applying the fine-blanking technology, the significant improvement of the component should be obvious. As the components are designed with a good shape, smooth surface, and precise size, they can be ready for assembly without any further secondary operations. The productivity cycle time is increased and the component costs are significantly reduced.

2. Heat Treatment

Heat treating is the operation of heating and cooling a metal in its solid state to change its physical properties. For example, steel can be hardened to resist cutting action and abrasion, or it can be softened to permit machining. With heat treatment, internal stresses may be removed, grain size reduced, toughness increased, or a hard surface produced on a ductile interior.

Continuous Heat Treatment

The shears are carried on a conveyor side by side into a heating tunnel. Due to its productivity and cost efficiency, this is the most popular way to harden steel for general application. It minimizes oxygen contact with the parts with a fire curtain.

Vacuum Heat Treatment

For better quality, the scissors are placed in a vacuum chamber where the oxygen is extracted and heated up. The key advantage of vacuum heating is making a small grain structure that is tougher than one with large grain structure, so that it makes the shears sharper, more durable and more corrosion resistant.

It is very important to minimize oxygen contact with the parts. If steel comes in contact with oxygen in heat treating, the carbon will dissipate into the atmosphere, forming a decarburized layer of steel. This will result in the scissors’ edges cutting into each other and dulling very fast.

Induction Heat Treatment

For special application, some of our shears are double heat treated. For a proper tension between blades, and because the metal behind the cutting edge has the job of transmitting the cutting forces and standing up to the stresses, the shears are first hardened to become hard and brittle, then subsequently tempered to relieve quenching stresses and to provide a limited but necessary degree of toughness and ductility to protect the part from cracking.

3. Grinding & Polish

Grinding means to abrade, to wear away by friction, or to sharpen. In manufacturing, it refers to the removal of metal by a rotating abrasive wheel. Wheel action is vaguely similar to a milling cutter, which is considered a multiple cutting point tool. However, a grinding wheel is composed of many small grains bonded together, each one acting as a miniature cutting point. The grinding wheel is considered to have an infinite number of cutting points.

The finishing parts on grinding machines have cylindrical, flat, or internal surfaces. The surface of the part largely selects the grinding machine. Machines designed for special functions, such as tool grinding or cutting off, are designated according to their operation. The hardened blades then go through several grinding and polish processes.

Bevel Grinding to the Backside of Blade

There are flat-ground bevels and hollow-ground bevels. In shearing action, the shears with hollow-ground bevels are with less force. The bevel angle, small angle/less force or larger angle/more force, is required in closing a shears. But when determining the bevel angle, we have to consider the thickness of blade. The thinner blade with a larger angle will scarify the clamping force of blades through the entire length of cut or else tearing may occur rather than cutting.

Cutting Edge Grinding

The cutting angle shears may have a very thin or thick blade with a different cutting angle. Both blades can be cutting blades in the same or different angle, or one of them is anvil in any combination. Most are designed for specific uses; preferences are determined by the end user.

Besides the above-mentioned various cutting angles with different applications, the shears also can be distinguished between straight blades and curved blades. The curved blades offer consistent closing angles to reduce a force that pushes the workpiece toward the tips. It can be one curve or a combination of different curves.

Inside Chamfer: The shears designed for garden use, or for any other rough cuts, may cross-cut its blades due to the cross force. To avoid a cross-cut and chipping of the blade, an inside chamfer is required at the tip of cutting edge.

Polish: For an easy cut and to maximize the stainless feature, the surface should be highly buffed. After grinding, the grit leaves a rough surface which looks like a ragged groove under microscope. Moisture or other foreign particles can be trapped in the cracks and the steel could get rusty.

Notch: When cutting a tougher or rounded shape workpiece, it is best to place the workpiece as close as possible to the fulcrum. The tougher the workpiece, the harder the force will push it out of position. The notch can hold the workpiece and reduce the closing angle of shears in turn with less squeezing force required.

Serrations: These are fine lines or teeth ground into the edge of one blade. The serration holds the workpiece, keeping it from being pushed forward.

Hollow Grinding in Inner Blade

The high-quality shears made by Vampire Tools™ are hollow grounded. The advantage of hollow ground shears is to reduce the friction resistance and prevent the material jammed in shearing action. This not only increases productivity, but also reduces operator fatigue.

Vampire Tools™ designs their own machine, which can be adjusted to a desired hollow depth, and processes a consistent hollow side of blades for quality.

Vampire Tools™ are also able to grind spiral hollow blades. This can vary by the clearance angle on the cutting edge and compensate the squeezing force while the cutting point is moving forward to tips of shears.

4. Surface Treatment

The process of surface treatments, more formally known as surface engineering, tailors the surfaces of engineering materials to:

• Control friction and wear.
• Improve corrosion resistance.
• Vary appearance, e.g., color and roughness.
• Change physical property, e.g., conductivity, resistivity, and reflection.

Ultimately, the functions and/or service lives of the materials can be improved.

Other Surface Finishing

Sandblasting  is used to clean, deburr, or etch a surface. The effect is similar to that of using sandpaper but provides a more even finish with no problems at corners or crannies.

Tumbling finishing  is used to burnish, deburr, clean, radius, de-flash, descale, remove rust, polish, brighten, prepare parts for further finishing, and break off die cast runners.

5. Handle Molding

To provide a comfortable grip, Vampire Tools™ adopts a human-centered design concept.  On traditional shears, the handles are even, meaning that both handles look the same and are the same length. One of the first and most popular ergonomic shears developed was the offset shears, where the thumb ring was brought forward. This allows your thumb to have a more natural movement and won’t force it opposite the ring finger when closing.  It is best to cut with the wrist straight.

In addition to the shape of handle, the material is also very important.  For different applications, there are some different concerns, such as skin acid, oil, electrostatic, toxic, recyclable, etc. Its physical feature is unbreakable, non-slippery, and easy to grip.

6. Assembly and Inspection

The tension system screw and nut and/or with washer assembly is not only pivotal for blades, but also provides an important function clamping the blades together while in shearing action. Thus, the material of tension system has to endure tensile force, pulling force, and shearing force that reverses back to the tension system. In addition, this mechanism is adjustable to stabilize the blades.  SUS 302, SUS 303, SUS 304 and AISI 435 are good choices for these components.

The scissors with a screw mechanism provide good serviceability. It is the nature that the shears will wear off over time. Some types of the shears need to be taken apart for regrinding and readjusting.  The inexpensive scissors that are riveted cannot be properly grounded and readjusted. After assembly, to give the shears a smooth, efficient run with less force, adjusting and straightening the scissors is craftwork that only few people can master.

Surface. Some shears are plated with chromium for specific application. To maximize the stainless feature, the surface is highly buffed. Scissors made of non-corrosive stainless steel are either burnished or sandblasted to give a fine matte effect, coated in Teflon (black or colored).

Quality. To ensure a high-level of consistent quality, Vampire Tools™ executes thorough, extensive control of the material, hardness, and grinding of the scissors and all craftwork in whole process.

7. Maintenance

One of the most common types of corrosion on shears is pitting due to lack of cleanliness. To prevent the metal from excess oxygen requires you to maintain the corrosion-resistant surface. Keep shears clean and dry and oil the shears after cleaning.