Medical device hard wire cutters. What gives them their edge?

Choosing the wrong cutter can be like trying to cut cement with a knife. If the cutters aren’t harder than what they’re cutting, they can be damaged or chipped. Furthermore, the cutters need to hold up to cleaning and harsh environments such as the sterilization process used in autoclaves. Any way you slice it, buying the right pair is critical when cutting the extremely hard materials often used in the medical device manufacturing of catheters, stents, pacemakers and more.

Steel hardness

The bulk of hard wire cutters are made with steel carbide and manufacturers generally spend hours researching and developing special, proprietary heat-treating processes. These complex methods determine the hardness of the cutter edges as measured by the Rockwell Hardness (HRC) scale, based on ability to indent the material. Cutters are then extensively tested for durability and capability.

Steel with a higher HRC number will have higher edge retention but will be less tough. Steel with a lower rating will have less edge retention but increased durability. Generally, less edge retention will require more blade reconditioning, as most cutters can be sharpened. Although harder steel may hold an edge longer, it can also be more brittle. Some alloys can actually become too hard and can shatter.

What gives these brands their competitive edge?

Each cutter manufacturer comes to the table with individual specialties, whether it be a proprietary hardening process, unique handles or springs, joint style, cost, number of cuts, sharpening (# of times), resistance to corrosion (autoclave environments) or edge sharpness.

Check out the different options offered by medical device cutter manufacturers Aven, Erem and Swanstrom.

Aven - Accu-cut Series

What they cut
  • W series - stainless steel, nickel, nitinol (nickel and titanium), tungsten; cutting edges 67 HRC
  • T series - cuts thicker hard wire than W series; solid tungsten/cobalt alloy steel cutters; up to 81 HRC blades
Features

ESD-safe grips, dual-leaf springs, box-joint construction to ensure precise jaw alignment, tungsten carbide blades brazed into jaws

Made from: Carbon steel with tungsten alloy inserts

Applications: Stents, catheters

Cut Options: Flush, semi-flush

Price Range: $140 to $160

Erem - Various

What they cut
  • Stainless steel, Vectran/braided wire, 303-316 & MP35N steel, nitinol, Kevlar
Features

ESD-safe handles, Magic Spring, up to 1 million openings, tungsten carbide tips

Made from: Tungsten carbide-edged steel

Applications: Stents, catheters, guide wires

Cut Options: Semi-flush, Full flush, Super flush

Price Range: $164 to $272

Swanstrom - M Series

What they cut
  • Piano wire, tungsten, gold, platinum, Vectran®, nitinol, most stainless including MP35N-V, PTFE-coated materials
Features

ESD-safe, adjustable Scrivet® joint, proprietary heat treating process, traditional or ergo handles, 18-21 EMS finish

Made from: Carbide steel

Applications: Stents, mandrels, catheters, guide wires

Cut Options: Semi-flush, full-flush, super-flush

Price Range: $65 to $175

More Cutter Considerations

Cost

The cost of a cutter can vary greatly. You must decide how long you want to use the cutter. Do you prefer a cutter that can be reconditioned a few times or buying one more often to avoid going through the re-sharpening process?

Fit and Feel

Cutter manufacturers offer a broad assortment of precision-based options depending on the material to be cut. Some manufacturers offer the opportunity to mix and match portions of the cutter, such as a choice of handles (ergo or traditional). Ultimately, a cutter of choice has a sweet spot for the operator, such as cutter comfort and breadth of what it cuts.

Form and Finish

When buying cutters, you’ll have the opportunity to choose from various configurations – head shape, length of handle, type of handle, width of the cutter head, length of the blades and much more.

Unlike common standard cutters which pinch the wire, hard wire cutters actually fracture the metal instead of pinching the wire. What type of termination/finish do you want to create? Semi-flush, flush or full flush? And, can you make accurate, repeatable cuts?

In some applications, it’s absolutely imperative that you make a particular style of cut. For example, if you’re cutting very hard, fine nitinol wire (expandable mesh) for use in a stent, you’ll want to make a near-perfect, full flush cut, i.e. zero pinch.