Case Study: 30 Flexible TPU Belt Clips for a Hospital Device-Integration Team
In spring 2026, a device-integration team at a hospital system asked us for six belt clips for a handheld wireless communication device they support. Within weeks, a test group reported that a few had snapped at the opening point. We tested alternatives, sent the team one sample clip in flexible TPU (95A), and the team then issued a purchase order for 30 clips in that material — printed with eight perimeter walls and solid construction. This case study covers what broke, why the material changed, and how a small 3D printing shop works inside hospital purchasing, told without the customer's name.
Who this is for: clinical engineering, device-integration, biomedical equipment and facilities teams — and the procurement staff who buy for them — who need a small quantity of accessory parts (clips, holders, mounts, brackets) that nobody sells off the shelf.
What did the team need?
The request was as plain as they come: a quote for six clips for a handheld device the team supports. We sent the invoice within a couple of hours and committed to have them printed by the end of the day. Six is a real order here; so is one.
A belt clip is a deceptively hard part. It has to grip firmly, open wide enough to get onto a belt or pocket, and do that hundreds of times without loosening or cracking. In FDM printing that is a design-and-material problem, and the first batch showed us exactly where.
Why did the first clips break?
About two weeks in, the team came back with feedback that was specific and useful: a few of the clips had already broken, and the failure was consistent — they snapped when opened with force. Their question was the right one: is there a material that can take being opened harder than intended?
That framing matters. The clips were not failing in ordinary use; they were failing at the edge of use, when someone opened one wider or faster than the design expected. On a hospital floor, edge-of-use is normal use.
Here is the mechanical reason. A clip works by bending. A rigid FDM plastic bends a little and then cracks, and it cracks first along the layer lines at the highest-stress point — the root of the clip arm, where the bending load concentrates. You can design around it (thicker root, larger fillet radii, orient the layers along the arm rather than across it), and we do. But when the requirement is "survives being opened with more force than expected," the honest answer is usually a material that wants to bend in the first place.
How did we choose the material?
Our first instinct was nylon — tough, fatigue-resistant — or a multi-material clip with a flexible hinge zone in an otherwise rigid body. We told the team we would test before quoting, because a quote for a part we are not sure will survive is not worth sending.
The material that won was flexible TPU in a 95A grade — firm enough to keep its grip on a belt, soft enough to open wide without cracking. Rather than promise it, we sent one sample clip in TPU 95A for the team to use. After the sample had been in their hands, the team issued a purchase order for 30 clips in that material, and the order carried the exact spec from our quote: eight perimeter walls, solid part construction, bone-white finish.
In a flexible part, the walls are the part. Solid construction removes the internal voids where a tear starts, and eight continuous perimeters put uninterrupted extrusion lines around the clip arm in the direction the load runs. It costs more print time per part than a hollow clip would — a price worth paying for a part that has already failed once.
How the candidates compare for a snap-open clip:
Rigid printing plastics (PLA, PETG, ASA): stiff, dimensionally precise, cheap and fast to print. Limitation: a snap or hinge feature is stressed across layer lines, and overload ends in a crack rather than a bend.
Nylon (PA): tough, good fatigue life, forgiving under repeated flexing. Limitation: absorbs moisture, which softens it over time and complicates printing; it still cracks eventually at a sharp root if the design has one.
Flexible TPU: bends and recovers, very high elongation, abrasion-resistant. Limitation: it grips by squeeze rather than by a stiff latch, prints slower, and is the wrong choice where a part must stay rigid under load.
Multi-material (rigid body, flexible hinge): the best of both on paper. Limitation: the bond line between materials is its own failure point, and it adds setup and cost that a 30-piece run rarely justifies.
Material choice is always a conversation about where the part lives — the materials rundown covers the full list of what we print.
How does a 30-piece run work with hospital purchasing?
Before the first batch, we registered as a supplier in the health system's purchasing platform — the standard forms, tax paperwork, and a check that the legal company name matched. When the 30-piece order was approved, it arrived as a formal purchase order that listed our quoted spec line for line: material, wall count, solid construction, color. That is exactly what you want a PO to say, because it means the print settings are part of the contract, not a verbal understanding.
Invoicing taught us something. We submitted through the vendor portal and assumed that reached accounts payable. It did not; the invoice had to go to the AP mailbox directly, and their team walked us through it. If you are a small shop selling into a hospital or university, ask on day one exactly where invoices go and who confirms receipt.
The timeline, in round terms:
Mid-April: quote and invoice for six clips, with a same-day print commitment.
Late April: supplier registration completed with the health system.
Early May: feedback — a few clips broke when opened with force; a tougher material requested.
Early to mid-May: material testing; one TPU sample clip sent for real use.
Mid-May: quote for 30 TPU 95A clips — eight walls, solid construction, bone white.
Late May: purchase order issued for the 30.
Early June: invoiced through the health system's accounts-payable process.
Since then: the same team has asked us to quote a second part — a batch of holders — and a colleague who had seen the clips reached out about an unrelated replacement part.
What we do not claim for hospital-environment parts
These clips are accessories. They hold a device on a belt. They are not medical devices, they do not touch patients, and nothing in this article should be read as a medical or laboratory certification.
To be direct about it: we do not hold ISO 13485 or an FDA registration; we do not claim biocompatibility, sterilizability, or autoclave survival for any FDM part; and if a part needs any of that, we will say so and point you to a supplier who qualifies. What FDM does well in a hospital setting is the non-clinical hardware around the equipment — clips, holders, mounts, brackets, organizers, cable management — where the requirements are fit, durability, and a quantity nobody stocks. Those we treat like any other jig, fixture or holder: printed to your geometry, in a material matched to the duty.
Where it went from there
The clip file is on record with its settings, so the next 30 — or the next six — is a reorder, not a project. Same part, same spec, every run, with no tool to amortise. The team's second request, a batch of holders, is in the quote stage as this is written; we will add it here if and when it becomes a part we can talk about. That is the honest scope of this case: a design that failed in the field, a material change proven with one sample before anyone bought thirty, and a purchasing process that now works.
It is the same path we describe in the nylon reject-chute case study — a validated design carried into a small production run without waiting on tooling, which is what our prototype-to-production service exists for. For a broken or discontinued part with no drawings, the replacement parts service starts from the worn original instead of a file.
What this means if you need clips, holders or mounts
A small quantity is a real order. Six clips got this job started; the 30 followed because the six were used hard and reported on honestly.
Feedback with a failure mode is the most valuable thing you can send. "They snap when opened with force" told us more than "they broke."
A sample before a batch costs a few days and protects the batch. Ask for one when the part has to flex, snap, or take abuse.
Say what the part has to survive. We match the plastic to the duty — or tell you when printing is the wrong tool.
Purchasing is normal here: supplier registration, a quote to spec, a formal PO, and invoicing through your AP.
We print in Columbia, MO and St. Petersburg, FL (both locations by appointment) and ship to all 50 states. Most parts ship two to three days after approval; exact timing is confirmed when we review the job.
Frequently asked questions
Can you 3D print flexible parts like clips, straps and grommets?
Yes. Flexible TPU is a standard material here, and it is the right choice when a part has to bend, snap open, absorb impact or grip by squeeze. Its limits: it is slower to print than rigid plastics, it holds looser tolerances on fine features, and it is the wrong choice where a part must stay stiff under load.
Why do 3D printed clips break, and how do you prevent it?
FDM parts are weakest across their layer lines, and a clip concentrates bending stress at the root of the arm. Prevention is design plus material: thicker roots and generous fillets, layer orientation along the arm, more perimeter walls, and — when the part must survive rough handling — a flexible material such as TPU rather than a rigid one.
Do you work with hospitals and universities on purchase orders?
Yes. We complete supplier registration, provide tax paperwork, quote to a written spec, accept formal purchase orders, and invoice through the institution's accounts-payable process. Tell us early where invoices need to go; it is the step most likely to stall.
Are your 3D printed parts approved for medical use?
No. We print accessories and equipment hardware — clips, holders, mounts, brackets — not medical devices. We do not claim biocompatibility, sterilizability or autoclave survival for any FDM part, and we do not hold ISO 13485 or FDA registration. If your part needs those, we will tell you plainly.
What do you need to quote a clip or holder?
A model file (.STL, .STEP, .OBJ or .3MF, zipped) gets a same-day quote. No model? Send the original part or clear photos with a scale reference, and we can create the CAD as a quoted line item. Either way, tell us the use, the environment, the quantity, and what the part has to survive.
Is there a minimum order?
No. Six clips was a normal order and 30 was a normal run. Your file stays on record for reorders at the same spec.
Need small-batch clips, holders or mounts?
Send the file — or a photo of the part — and what it has to survive. You will get a same-day quote, a straight answer on material, and a sample before the batch if the part has to flex. Request a quote for small-batch parts or text 630-485-9984.
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