APPLICATIONS

Autoinjectors

Custom springs, power packs, and precision metal components for autoinjectors, engineered to support accurate, comfortable, reliable drug delivery

Autoinjectores
Feature

Springs, stamped metal parts, and power packs engineered for high- and low-viscosity drug delivery, including today's thicker biologics, to support reliable performance

Feature

Precision contact components and conductive metal parts for connected, smart-cap autoinjectors

Feature

Automatic spring-based needle shielding before and after injection for consistent patient safety and protection

Autoinjector Parts
AUTOINJECTORS

Precise administration

Autoinjectors deliver medication subcutaneously or intramuscularly with precision the patient doesn't have to think about. As portable, single-use pens, they support therapies ranging from anaphylaxis and diabetes to the fast-growing class of GLP-1 and biologic treatments. Behind that simplicity sits a tightly engineered set of metal components, and getting them right is what makes the difference between a device that works every time and one that doesn't.

Auto injector pen
RELIABILITY

Created for everyday use

These devices are used every day, often in stressful or emergency moments, so they have to work reliably every single time. In that setting, a well-designed autoinjector removes hesitation from self-injection and lets patients — or a bystander in an emergency — deliver the dose confidently, with no steady hand required. The stored energy in the spring does the work.

Autoinjector Springs
COUNT ON US

Springs and metal parts for every need

We manufacture precision components for 2- and 3-step autoinjectors that give patients clear audible, visual, and tactile feedback at each stage. At the same time, a spring retracts and shields the needle after injection, while our springs are engineered to handle both high- and low-viscosity formulations, including concentrated biologics that place heavy demands on delivery force and dual-chamber drug delivery. Depending on the device, that means compression, torsion, constant-force, or telescopic and concentric springs.

Springs are only half the story. The stamped and formed metal parts they act on — spring seats, plunger rods, retainers, triggers, latches, and structural frames — hold the mechanism in alignment and have to perform under the same loads. In production, we use progressive-die stamping for high-volume runs and multislide (fourslide) forming for intricate, multi-bend parts, feeding the material along its grain direction for better fatigue resistance. For connected injectors, smart caps rely on precise, repeatable electrical contact, which our contact components and conductive parts are built to guarantee.

PRODUCTS

Together, we make the perfect solution for your autoinjector

The earlier we join your project, the more we can optimize. We co-engineer with pharmaceutical companies, CDMOs, and device manufacturers by refining spring force, delivery control, and component geometry against your drug's viscosity profile and use case, then validating through testing and simulation before scale-up.

Manufacturing runs to ISO 13485, with clean-room cleaning and packaging, machine-vision inspection, load testing, and full material certification. From rapid prototyping through global serial production, we bridge the gap between design concept and reliable, high-volume supply.

Products
Compression springs
Wave springs
Constant force and power springs
Assemblies & power packs
Torsion springs
Tension springs
Stamping & bending
Contact springs

Frequently Asked Questions

What metal components does an autoinjector actually need?
Three families work together. Springs store and release the energy: a compression drive spring for the dose, a shielding spring for the needle guard, and constant-force springs for steady delivery of thicker drugs. Stamped and formed parts make up the structure that spring energy acts on: plunger rods, spring seats, retainers, triggers, latches, and the frames that hold everything in alignment. Contact parts handle the electrical side in connected devices. RPK Medical supplies all three as a single validated package, which removes tolerance stack-ups between suppliers.
What types of springs are used in an autoinjector?
A compression drive spring stores the energy that pushes the plunger and delivers the dose; a needle-shielding spring extends the guard before and locks or retracts it after injection; and constant-force springs maintain steady delivery force across the full stroke for higher-viscosity drugs. Constant-force springs are flat metal ribbon coils rather than helical springs, which lets them hold near-constant load through a long extension.
Do you make the stamped metal parts as well as the springs, and what is multislide?
Yes. Alongside springs, RPK Medical produces the stamped and formed metal parts that give an autoinjector its structure and function: spring seats, plunger rods, retainers, clips, triggers, and latches. Progressive-die stamping is the most cost-effective route for high-volume runs of simpler parts. Multislide (fourslide) forming shapes slit coil or wire from several directions at once, producing complex multi-bend parts such as intricate clips and formed contacts with less scrap and no carrier rails. Multislide also feeds the material along its grain direction, which improves fatigue resistance in parts that flex or carry load.
How do springs deliver high-viscosity biologics without hurting the patient?
Concentrated biologics such as monoclonal antibodies and long-acting therapies can be many times thicker than water, so the device needs more force to inject them within a comfortable window, often around 10 to 15 seconds. High-force and telescopic or concentric spring stacks release that energy in a controlled profile, and the stamped parts they act on are matched so nothing deflects or wears under the higher load. The result is a smooth delivery matched to the drug's viscosity, container geometry, and target injection time.
What are contact parts used for in an autoinjector?
Contact (contactor) parts are the conductive metal components that carry current or signal in connected, smart-cap autoinjectors, detecting cap removal, confirming the device has fired, or waking the electronics for dose logging. They must make reliable, repeatable electrical contact from the first actuation onward, so they are formed to tight tolerances with controlled contact force and clean, burr-free edges, and their materials are selected or plated for stable conductivity and corrosion resistance. The same multislide capability forms both contact springs and structural clips, so the electrical and mechanical parts integrate in one subassembly.
What is a power pack, and can it include stamped and contact parts?
A power pack is a pre-assembled, validated subassembly that combines the springs with the stamped and formed parts and, where needed, the contact components into a single unit the device manufacturer integrates directly. Supplying a complete tested pack rather than loose parts removes assembly steps, controls variability, and shifts qualification effort upstream. Because RPK Medical makes the springs, the stamped structure, and the contacts in-house, the power pack arrives already balanced as a system rather than assembled from three separate supply chains.
What quality standards and controls apply to your autoinjector components?
RPK Medical manufactures to ISO 13485 with clean-room cleaning and packaging, machine-vision inspection, load testing against the specified spring rate and travel, dimensional control on stamped parts, and full material certification and traceability. Autoinjectors are validated as needle-based injection systems under the ISO 11608 series, where component-level force, dimensional, and contact-integrity control feeds directly into system dose-accuracy and reliability testing.
Can you get involved early in device development?
Yes, and the earlier the better. RPK Medical co-engineers with pharmaceutical companies, CDMOs, and device manufacturers from the concept stage, refining spring force, part geometry, and contact design together against the drug's viscosity profile and use case, then validating through testing and simulation before scale-up. Designing the springs, stamped parts, and contacts as one system early carries through from rapid prototyping to global serial production.

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