Top 7 Manufacturing Challenges in Disposable Injection Pens

Disposable injection pens are widely used for therapies such as Insulin and GLP-1 drugs like Semaglutide.

As demand for biologic and peptide drug delivery devices grows, manufacturers face increasing pressure to ensure consistent performance, high yield, and scalable production.

However, achieving stable quality in high-volume automated assembly is not straightforward. This article outlines the top 7 manufacturing challenges in disposable injection pens—and practical solutions to overcome them.

disposable injection pen

1. Injection Force Variation

The Challenge

Inconsistent injection force leads to poor user experience:

Too high → difficult to inject

Too low → inaccurate dose delivery

Root Causes

Variable friction between components

Lubrication inconsistency

Spring force deviation

Solution

Implement 100% in-line injection force testing

Optimize lubrication process

Control spring parameters with tight tolerances

✔ Result: Smooth and consistent injection performance

2. Assembly Inconsistency

The Challenge

Device-to-device variation affects overall reliability.

Root Causes

Tolerance stack-up

Manual or unstable assembly processes

Lack of torque control

Solution

Use servo-controlled assembly systems

Apply torque monitoring with defined limits

Standardize component tolerances

✔ Result: High consistency across production batches

3. Device Jamming or Sticking

The Challenge

Jamming is one of the most critical failures in injection pens.

Root Causes

Misalignment of internal components

Poor engagement of inner rotation mechanisms

Assembly offset

Solution

Introduce precision alignment systems

Use vision-guided assembly

Optimize component design tolerances

✔ Result: Smooth and reliable device operation

Inner Rotation Pen Injector

4. Low Production Yield

The Challenge

High rejection rates increase production costs and delay delivery.

Root Causes

Uncontrolled process parameters

Lack of real-time quality monitoring

Solution

Implement real-time process control systems

Use automated inspection at each critical step

Identify and control key process variables

✔ Result: Improved yield and reduced waste

5. Lubrication Variability

The Challenge

Inconsistent lubrication leads to unstable injection force.

Root Causes

Uneven silicone oil application

Lack of process control

Solution

Use automated lubrication systems

Monitor coating volume and uniformity

Apply validation and calibration protocols

✔ Result: Reduced friction variability and stable performance

6. Spring Force Variation

The Challenge

Spring performance directly impacts dose delivery accuracy.

Root Causes

Supplier variability

Lack of incoming quality control

Solution

Perform incoming inspection and sorting

Control spring compression parameters

Use validated spring specifications

✔ Result: Accurate and reliable dose delivery

7. Lack of Traceability

The Challenge

Without traceability, root cause analysis becomes difficult.

Root Causes

No data collection system

Manual production tracking

Solution

Implement MES (Manufacturing Execution System)

Track each device with unique identification

Record torque, force, and assembly data

✔ Result: Full quality traceability and regulatory compliance

Why Process Control Matters for Pharmaceutical Companies

For pharmaceutical companies, injection pens are not just devices-they are critical components of drug-device combination products.

Manufacturing disposable injection pens at scale requires more than automation-it requires precise control of every critical process parameter.