Reverse Engineering A Guidewire Assembly

At Modern Grinding we often get inquiries to help medical device designers reverse engineer a guidewire assembly so that we can manufacture something similar for their device or for their distribution business. It seems like a simple enough request. Modern Grinding is in the guidewire assembly business, how difficult can it be to slap a coil, safety ribbon and core wire together? It actually isn’t too difficult (for us), but we need to know the exact design. Here are some of the hiccups that occur when reverse engineering a guidewire assembly.

Guidewire Assembly Formed Core Wires
Guidewire Assembly Formed Core Wires

Guidewire Use Case

The most important part of a guidewire is how it is used. At Modern Grinding, we are contract manufacturers, we aren’t doctors. When someone comes to us and asks us to “copy” a guidewire, we don’t always know that exact guidewires use case. If we were to get something wrong, that can affect how the guidewire performs in surgery. Often foreign distributors will try to gloss over that fact, and say just give us something close (to another product in the market). At Modern Grinding, we take a deep concern for how our guidewires perform and we won’t accept “close”.

Guidewire Concerns

There are many small pieces of the puzzle which affect how a guidewire performs. How is the core wire connected to the coil? Is it welded or glued or fused? What tensile strength is the core wire? This can affect it’s flexibility and propensity to return to its original shape. Was the core wire heat treated? This again can affect the shape of the core wire and how it returns to its original form. What dimensions does the core wire have and what dimensions do the coils have? How much of the coil is coated? What is the tip coated with? How is the handle connected? Are all forms of PTFE the same? Are all hydrophilic  and hydrophobic coatings the same? While these all seem like little details, when you combine them all, you can lead to vastly different guidewires that appear the same.

New Guidewire Designs from Doctors

When doctors reach out for help, I feel bad if we can’t help. Often doctors come to us with a problem that they recognize with a pre-existing device. They are in the perfect position to come up with a new guidewire design that could better serve patients and help other doctors as well. The problem is that doctors don’t realize how difficult it can be to reverse engineer a product and then make a fairly similar guidewire assembly. We can do it, but we need to be able to nail down all of the key characteristics (see concerns section above) before we can start to make alterations on the wire. It takes a lot of engineering time to reverse engineer a complex product which is used in surgical applications.

This post wasn’t meant to scare anyone, just to let you know what goes into reverse engineering a guidewire assembly. We can do it, but it typically takes a couple days in engineering time, we aren’t able to just “copy” an existing wire without going through a very refined process.

Medical Device Assembly Process

As Modern Grinding grows and starts to develop manufacturing processes for a variety of products, we are getting into more and more multi-step medical device assembly processes. Our capabilities now include wire forming, wire grinding, coiling, microcoiling, welding, electropolishing and metal stamping.

Multi-Filar machine part of medical device assembly
Multi-Filar machine part of medical device assembly

One major product that we manufacture and assemble is guidewires. Many guidewires include a ground core wire (also referred to as mandrel), a coil (or microcoil) and a safety ribbon. These multiple parts typically are formed and welded together. While it would seem like this is a simple medical device assembly process, during the prototype phase it can be very time consuming to nail down the correct process. For one, your machines open up at different times. If you are trying figure out the correct process to form your ground core wires, you might need to try several different core wire designs. Once you have manufactured your core wires, you might realize that you need a different design once you get to the forming stage. This is fine if your grinding machine is always, open but ours rarely is, so you need to wait until machines open up to start over.

We recently started to pick and choose components of the six sigma process program to create a more robust project management process for medical device assembly. In the past, we did this type of project management in our heads, but as our production capabilities became more complex we realized the need for this type of system. Along with the principles of six sigma, we relied on the lean software principles of starting with a minimal design for project management and working with the main customers to create a product that everyone could use.

The main goals for me were to make sure that when we get a medical device assembly job, we get buy in from all of the departments we will be working with and we get confirmation from each department that they can accomplish the job within a given time frame. In the past, managers would take responsibility for department that they didn’t run and when a project started to get hard, the buck would get passed.

Here are a few tips from our medical device assembly project management experience:

  • Have a manager responsible for each step in the process
  • Think about alternative process routes while developing your process
  • Put your process on paper, from step 1 to shipment

Does anyone use simple project management tools for medical device assembly? We would love to hear about your trials and successes.