Control Plans
#Understanding Control Plans
A control plan is a quality tool that highlights key product specifications and how/where they will be confirmed before deeming a product good to ship to a customer or the next downstream step.
Think of a control plan as your quality roadmap—it guides you through the critical checkpoints in your manufacturing process, ensuring that your products meet specifications at each stage.
#Key Elements of a Control Plan
A comprehensive control plan typically includes:
- Product specifications: The critical characteristics that must be controlled
- Measurement methods: How each specification will be measured or verified
- Sample size: How many units will be inspected
- Frequency: How often inspections will be performed
- Control limits: The acceptable range for each measurement
- Responsible parties: Who will perform each inspection
- Corrective actions: What to do if specifications are not met
#Types of Control Plans
#100% Inspection
- Every unit is inspected for critical specifications
- Used for high-value components or products
- Provides maximum quality assurance
- Can be labor-intensive and costly
- Often used for safety-critical components
#Sampling Inspection
- A subset of units is inspected in each batch
- Balances quality assurance with efficiency
- Can be statistically valid if properly designed
- Reduces inspection costs compared to 100% inspection
- Common for high-volume production
#Statistical Process Control (SPC)
- Continuous data collection and analysis
- Uses control charts to monitor process stability
- Identifies trends before they become problems
- Requires training and discipline to implement
- Provides early warning of process changes
- Learn more: statistical process control
#Implementation Strategy
When starting a new product, it’s a good idea to plan on doing 100% inspection of all key specifications, setting up tooling and processes to execute them efficiently. As you scale, you should be building more consistency into your product Value Stream, and you’ll learn what parts of the control plan are good candidates to wind down from 100% inspection to more automated, less labor-intensive processes.
In doing so, you need to be sure to ask yourself “Is the customer still being protected from poor quality with this change?” The target is not just to remove quality inspection points, but to set up your process where you are building quality in to each step, minimizing and mistake-proofing opportunities for error, and then to have the lightest level of inspection possible while still ensuring sufficient quality control.
Additionally, a Failure Mode and Effect Analysis (FMEA) can be a helpful analytical tool to understand what types of controls will be necessary in various parts of the Value Stream.
#Real-World Example
Consider a manufacturer of precision machined parts:
Initial approach: 100% inspection of all critical dimensions using manual measurement tools. This ensures quality but is slow and labor-intensive.
Evolved approach: After process stability is demonstrated, the manufacturer implements SPC for most dimensions, with automated measurement equipment collecting data continuously. They maintain 100% inspection only for the most critical safety-related dimensions.
The result? Reduced inspection costs, faster throughput, and maintained quality levels.
#How Threaded Helps You Implement Control Plans
Threaded’s Standard Work module provides powerful tools for implementing and managing control plans:
- Digital Control Plans: Create and manage control plans in a collaborative digital environment
- Process Integration: Connect control plans directly to work instructions
- Data Collection: Record inspection results directly in the system
- Statistical Analysis: Analyze trends and identify opportunities for improvement
- Action Tracking: Create and assign actions for any issues found during inspections
By centralizing your control plans in Threaded, you ensure that everyone in your organization has access to the most current information and can contribute to continuous improvement efforts.
#How Threaded Helps You Implement and Sustain a Control Plan
Learn how Threaded can help you define and manage quality checkpoints in your process, seamlessly integrated with the rest of your work instructions in our Standard Work guide.
