Stainless Steel Coils vs. Nitinol Coils

Modern Grinding has the capabilities to manufacture both stainless steel coils and nitinol coils, and some of our clients have asked us what the difference between the two is. The difference is mainly the amount of nickel and titanium present (sorry that was a very dry metallurgy joke – nitinol is mainly a combination of NIckel and TItanium which is how they derived the name for the metal). Obviously that is the difference, but was is the difference in performance, cost and in production.

In performance, nitinol wire has the property of not kinking. It takes a lot of force relatively to make nitinol kink. Nitinol is more flexible. These two properties are very helpful in creating internal medical devices. Also nitinol has a memory property, the ability to revert back to an initial position when there is a change in temperature of the material. For instance within orthodontic devices, nitinol springs can try to either push teeth away from each other, in a open coil design or pull teeth closer together in a closed coil design. Nitinol can self-expand (compression) or self-contract (induction) depending on the needs of nitinol springs within your medical device.

Nitinol Coils

Stainless steel coils don’t have the shape memory property that nitinol contains. Stainless steel is best used if you need more rigidity in your coils or if you need your coils to more firm. Modern Grinding is able to achieve stainless steel and nitinol coils out of round or flat wire to very small tolerances. Stainless steel coils can be easier to weld with a stainless steel core wire. It is possible to weld nitinol but depending on the amount of material that you are welding, stainless steel provide a stronger bond. Don’t hesitate to contact Modern Grinding with your custom coil project today!

The cost of manufacturing nitinol springs and stainless steel springs varies as well. Nitinol typically costs more since it is not as prevalent of a metal within the materials supply chain. The material pricing difference is not as prevalent if the manufacturer has a long lead time to get material from an original raw material supplier.  Since coils tend to not be as heavy in material, the big pricing difference comes in secondary processes needed with coils. Depending on the number of processes that you need to do to the nitinol, your costs can add up, since nitinol is more abrasive material than stainless steel and since most finishing companies aren’t as accustomed to working with nitinol.

Hopefully this post provide a little insight into the differences between stainless steel coils and nitinol coils. We have an internal engineering department with experience designing coils with a variety of materials and designs. If you have specific questions don’t hesitate to give us a call!

Building A Grinding Machine

One thing that Modern Grinding prides itself on is being at the forefront of grinding technologies. Recently we identified an OD grinding process that wasn’t being served well in the market. It is a process that can be done, but mostly by high-end machines. The products that come out are somewhat commoditized, so it creates a conundrum. Do you make commoditized products on an expensive machine? Or do you build a low-cost machine specifically for one product? We decided to take the leap into machine making and we enlisted the help of undergrad engineers from Marquette University.

Machinery development is a new expertise for us. We have learned a lot about hardware design and the software to run it. This will not only help us run the new grinding machine but it will make us more comfortable making alterations to our existing machines if need be. Our hope is that we can make more grinding machines after this works out. We hope to automate the grinding process with the help of production robots.

Modern Grinding officially opened its doors in August of 2013. We started with a tool shop grinder. Once the home built grinder is in place we will have 5 grinding machines. Don’t hesitate to contact us with your next grinding project, we love testing the limits of grinding capabilities!


Custom Mandrels

As we have built our grinding operation we have come across a wide variety of parts that we didn’t really know there was a market for. One such market is high precision low tolerance custom mandrels. Mandrels are typically used in manufacturing to electroform or shape machined parts. Clients come to us when the mandrels they were using break or need to be replaced. They typically need the mandrels yesterday. We understand, we run a contract manufacturing facility with high customer demands and we know the pressure of lost machine time at the company.

Products such as depth mandrels, tunneling mandrels, coiling mandrels and tipping mandrels are fairly easy for us to accomplish with our advanced CNC grinding machinery. We are able to make small prototype lots or large productions lots alike. We have a variety of stainless steel and nitinol material in stock for fast turnaround of these types of parts.

Our sweet spot for mandrels is between diameters of .003″ and .1″. We are able to achieve multi-steps, flats and tapers to achieve complex forms for your manufacturing operation. Contact us today to find out how we can help.

Below is a sample of a couple of custom mandrels that we made:

Custom Mandrels
Custom Mandrels


Partially PTFE Coated Hypotube

partial ptfe coating
partial ptfe coating

This is part of our “medical device component questions answered section”. We often have medical device designers ask us questions and we answer them. We recently had a designer ask us how we would approach making a partially PTFE coated hypotube. The part has multiple sections that are coated and multiple sections that are uncoated. See photo above.

There are two ways to do this:

1. Precoated PTFE Wire. You can start out with a fully coated wire and then grind off the ptfe coated wire in certain sections. If you need to grind the wire anyways, this is probably the most affordable approach.  This version won’t be as visually appealing since there might be small amounts of PTFE coating left on the wire or the grinding might go slightly into the OD which might create a different service finish.

2. PTFE coating just sections of the wire. In order to achieve this, the coating company will mask sections of the wire which don’t get coated, prior to the coating. This approach will achieve more fluid results, but will be more costly.

If you have wire manufacturing questions don’t hesitate to send them in.

More OD Grinding!

Wow, things have been busy over here. I just realized that the last blog post we made was on Dec 2nd, almost 3 months ago. The funny thing is, I just logged in to let everyone know that we are expanding capacity again and noticed that the last post was to let everyone know that we have expanded capacity.

We are now able to make 300% more parts than we were just a few short months ago. We are also able to accommodate large production run guidewire and k-wire parts with much faster lead times.  We have backup capacity in case anything goes wrong. And we have more engineering knowledge and operator knowledge to help medical device designers with their next project.

Don’t hesitate to reach out today with your next medical device wire challenge.



Increased Wire Grinding Capacity!

Modern Grinding is excited to announce that we recently doubled our grinding capacity. This means faster turnaround for your next medical device project! It also means that we have backup capacity in the event of unforeseen circumstances.

Modern Grinding was founded in 2013 as a division of Custom Wire technologies. In a little over 12 months we have grown business substantially and our trusty little grinding operation is growing. We are thankful for all of the business we have received from medical device OEMS, researchers and distributors. We look forward to exceeding your expectations in 2015 and beyond.

Centerless Grinding Ads on Thomasnet

We have had many internal discussions about whether or not to use Thomasnet to advertise our OD centerless grinding services. On the pro-side, Thomasnet is a great solution that many engineers and product designers use to help source contract manufacturers for their projects. On the con-side is simply cost.

Our Google Analytics account shows a decent amount of traffic from our free Thomasnet account although to date we haven’t had a direct conversion from Thomasnet. Instead our conversions come from blog posts which educate our customers about how we approach manufacturing problems and the solutions we come up with. This helps draw educated customers that know whether or not we can solve their problem from the starting point.

We have decided not to advertise on Thomasnet to list our centerless grinding services but we will review again in the future.

Custom Medical Wire Component Forming

We are pleased to announce that we are now accepting wire forming projects for immediate production! It’s rare that we find ourselves with open machine time, but that is what we have right now, so don’t hesitate to send in your project today. Send along your custom medical wire component design and we will guide you through the design and manufacturing process for optimal production.

Many customers ask us “what types of medical wire forming components do you manufacture?” This is a difficult question. So many of the custom components that we manufacture are original and some are unlike anything else. The types of forming we can do are Bending, Forming, Flattening, Punching, Drilling, Coining, Threading, Straightening & Cutting, Welding, Coiling.

Reach out today for special pricing on our wire component forming machine.


Contract Manufacturer 510K Medical Device Application

Welcome to part 1 of a series of posts relating to the process for receiving approval for a 510K medical device design. We are a contract manufacturer and we recently had a client require that we have FDA 510K clearance for manufacturing their product. The product that we are planning to apply for is a class II medical device and has been in existence since the early 1900s. There are hundreds if not thousands of predicate examples of this product.

We wanted to create a series of posts which relate to this process since it seems like there aren’t too many good 3rd party sources which want to help manufacturers through this process and the FDA documentation can be overwhelming.

Find out CFR section and Class

We started out by identifying the CFR section and class our device fit into. The difference between classes is immense. Class I products often do not need 510K approval in order to be marketed. Class II products are usually based on predicate devices and must prove that they are similar. Class II products take on average about 6 months for approval. Class III products usually don’t have predicate devices and take a long time to get to market. The product that we are pursuing is Class II and we are crossing our fingers that this process only takes 6 months since we are complete novices.

I was able to get to the following page by searching for the type of product I was looking for, which in our case is a k-wire:


Figure out which type of 510K Application is needed

Next we identified which type of 510K application was needed (Traditional, Abbreviated or Specialty). We were hoping for abbreviated, it sounded like less work. Unfortunately, we needed to do traditional. We originally started our trying to read the different requirements for each type of application and found ourselves down a rabbit hole. The easiest way to find out which application is needed is to search the FDA website for predicated devices with the same CFR section number and it says what type of application they used. Since we are basing our application on a predicate device, I am looking to re-use as much work as I can.

I was able to get to find out the type of application I needed to use by typing the “k number” of a an existing k-wire approval and looking at the information:


tradional 510k application
traditional 510k application






That is it for today, now I know that I am going to need to do a traditional FDA 510K application and that it is a Class II device. For my next post I will take you through the initial stages of writing a traditional 510K application.

Medical Device Component Supplier

I’m not sure if its World Cup fever or a natural progression of the medical device market but in the last couple weeks Modern Grinding has received inquiries from companies in 5 different countries looking for a medical device component supplier. They came to the right place!

We are a Wisconsin based contract manufacturer of medical device components. Its exciting that we are able to help facilitate advancements in medicine all around the world. We’ve done work for top tier research universities, foreign companies and US government contracts in addition to our usual happy customers.

We are always looking for new partnerships and ways to expand our offerings. At Modern Grinding we have extremely high levels of quality and engineering as well as ISO 13485 and ISO 9001 accreditations for medical manufacturing. Don’t hesitate to contact us if you are in need of a medical device component supplier.