The Articulating Joint as
seen here with individual
links connected together
via laser welded springs,
demonstrates the
precision capability of
stamped assemblies
and components


I Can't Believe It's A Stamping!®

Case Study: Endoscopic Device Articulation Joint –
Laser Tube Assembly Conversion

A major medical device manufacturer was developing an endoscopy device for minimally invasive surgeries. The design requirements specified a low-cost
articulating tube that could be controlled by guide wires during surgery. The
articulating tube, also known as the A-joint, would allow a surgeon to insert
various instruments inside the tube while performing a procedure.

After several years of development and costly design proposals, the customer
asked Okay to help develop the A-joint as a patent-pending stamped
stainless steel link-and-spring assembly to meet their cost/design goals.
We began by partnering with the customer to understand the
critical application requirements.

Manufacturing the A-joint is very challenging because of the complex welding assembly process, the tolerances on key dimensions and target cost. The initial manufacturing method our customer considered was laser cutting stainless steel tubing and welding springs to the individual links. For prototypes and low-volume applications this method is very cost effective. For higher-volume production requirements, however, a metal-stamped and welded assembly is much more cost effective.

Springs welded to individual links shown without
any locating features. This approach required a complicated welding fixture to maintain position
of the links

Okay invented a patent-pending process in which individual joint links are stamped and interconnected as a complete set to maintain their locations during the articulation joint welding assembly. First, all of the inter-connected flat links are joined together via laser-welded springs. Next, the links are separated. Then the assembled A-joint is formed into its finished diameter. To reconnect the open ends of each link, a laser operation seam welds the last row of internal springs across each link from end to end. This innovation keeps the (14) individual A-joint links in position prior to welding the (28) springs in place.

These proprietary manufacturing techniques built an A-joint at a significantly lower cost than other methods. Additionally, this new technique can help create solutions for a wide range of medical and non-medical articulation joint applications with two very significant benefits: consistent quality and lower cost.

Fast-Track to Production
Thanks to Okay’s Production Proven Prototyping® process we were able to utilize the same tooling concepts, sequence of operations and grain direction that will be used in the production tool. Replicating the stamping and manufacturing process during the prototype stage can minimize costly changes later in the project that would not have been identified using machining or other prototyping methods. For this application, component strength, cracking, surface finish, burrs/edge condition and feature tolerance capability are a few of the concerns we assessed and addressed.

Stamping and laser-welded assembly also significantly reduced the capital cost of tooling and pre-production over other manufacturing methods.

The Bottom Line:
Okay partnered across the engineering spectrum with our customer to develop a new way to manufacture a highly sophisticated component. Together, we significantly lowered the cost while maintaining critical features. The end-process is controlled, monitored and maintained to produce a high quality part consistently. Most importantly, the customer got a better part for less.

Main Benefits:
1. The customer is receiving an extremely tight tolerance stamped assembly with (28) springs and high process capability at a significantly lower cost than a laser cut tube assembly.

2. With the automated laser welding operation and integration of the automated roll forming operation, every part meets the print specifications without requiring secondary operations.

This research and development effort uncovered opportunities for this technology to benefit customers in several industries who can reduce costs with stamped articulation joints instead of using more costly manufacturing processes.