YOUR MISSION: WIRE STRIPPING
(Should you choose to accept it)
- Remove PTFE coating in multiple, evenly-spaced 2″ sections from a stainless wire.
- The delineation from coating to clean wire should be <0.005″.
Your materials to complete this mission:
- a manual Comco MicroBlasting system.
- one able-bodied operator.
- 100 pieces of ss wire, half of which are 86” in length, the other half 43”.ODs are 0.020” and 0.016” respectively.
Ok. This task is not usually considered a “mission”; but it is a common challenge for the manufacturers in the medical industry and applicable to anyone working with PTFE wire or coil, PEEK tube, Nitinol tube, stainless tube, and needles.
It also allows us to have a little fun while we shamelessly plug a handy-dandy addition to your blasting system that will save time, money, sanity; and most importantly, help you complete this mission with speed, precision, and accuracy.
Before You Blast
We catalog PTFE coating removal under the umbrella of “Selective Cleaning“. While controlled erosion is the process of carefully removing layers of one type of material to carve channels or features; selective cleaning is the process of selectively removing unwanted material to reveal another. Often, selective cleaning involves the removal of one type of material from another type—like, a ductile layer from a brittle, or vice versa.
Abrasive selection is key to successful selective cleaning because it often involves two different materials. For this mission, a gentle abrasive like sodium bicarbonate can remove the top polymer layer without damaging the underlying wire.
The Single Nozzle Option
Now that you have your abrasive, the task seems relatively straightforward, right?
- Fixture your nozzle.
- Feed the wire through the blast cabinet to the starting point.
- Press the footswitch and blast.
- Turn the wire and blast again.
- Slide the wire to the next point and repeat.
The wire shown in the video is thin and relaxed. It bends and whips around in the blast stream. Rotation at a consistent pace is tricky with a wire this lax. It was hard to get a sharp delineation, and exact duplication will be impossible. This is what the wire looked like following the single-option blast:
Coating removal with single fixtured nozzle- messy delineation and duplication, impossible.
mission: NOT accomplished.
The Ring Nozzle: When 5 Nozzles are Better than One
(Here comes that shameless plug.) Fortunately, you have high standards. You value precision, and you recognize that time is precious. You use the Ring Nozzle.
The SP1906 Nozzle Array, or the Ring Nozzle, is designed to uniformly blast the outside diameter of wire or tubing simply by feeding the targeted part through the center of the array.
- No rotation required.
- No masking required.
- 360° of coating removal in one swift blast.
Take a look:
What is the Ring Nozzle?
The Ring Nozzle consists of three major components: the nozzle array assembly, a splitter, and two guide bolts.
NOZZLE ARRAY ASSEMBLY
Configured with five MB2520-30 Hi/Performance nozzles (custom options available); the nozzle array assembly is designed to spread the abrasive flow uniformly over a circular cross-section.
The splitter divides a single abrasive stream from your blaster into multiple uniform abrasive streams.
Guide bolts ensure the part is fed through the center of the blast stream and provide a masking feature when a part requires only partial blasting. Opening sizes are available from 0.020″ to 0.125″. Screwing the bolts in or out adjusts the length of the blast region. Stop wheels are used for stop points for the blasted part and ensure a repeatable blast position and length. The standard stop rod is 6″ (152 mm long), but longer stop rods are available upon request.
Q: What has 5 nozzles and blasts uniformly 360° on a targeted part to a sharp delineation?
A: The Ring Nozzle.
Fig – SP1906 5 Nozzle array or the Ring Nozzle
Q: How sharp is that delineation?
Coating removal from a coil using Ring nozzle, delineation <0.003″
Q: What do results look like on other materials?
A: See below:
Q: Who successfully completed this mission?
A: You did. (Don’t worry, this screen will not self-destruct.)