Production Planning and Control

Production planning and control encompasses the systems, processes, and methodologies that orchestrate manufacturing operations from order receipt through product shipment. In electronics manufacturing, where product complexity, component diversity, and demand variability create significant challenges, effective production planning is essential for meeting customer commitments while optimizing resource utilization and minimizing costs.

Modern electronics manufacturing requires sophisticated planning systems that balance multiple competing objectives: maximizing throughput, minimizing work-in-process inventory, meeting delivery commitments, and maintaining quality standards. The integration of enterprise resource planning systems, manufacturing execution systems, and lean manufacturing principles enables manufacturers to achieve operational excellence in increasingly competitive global markets.

Production Scheduling and Capacity Planning

Production scheduling transforms customer orders and demand forecasts into detailed manufacturing plans that specify what to produce, when to produce it, and which resources to use. Capacity planning ensures that sufficient resources are available to execute these plans while identifying constraints that may limit production capability.

Demand Planning and Forecasting

Accurate demand planning forms the foundation of effective production scheduling:

Historical analysis: Examining past sales patterns to identify trends, seasonality, and cyclical variations that inform future demand predictions
Customer forecasts: Incorporating customer-provided demand forecasts, particularly for key accounts with long-term supply agreements
Market intelligence: Considering market trends, competitive dynamics, and economic indicators that may affect demand
Collaborative forecasting: Working with sales, marketing, and customers to develop consensus demand projections
Forecast accuracy tracking: Measuring forecast versus actual demand to improve prediction methods over time
Safety stock calculation: Determining appropriate inventory buffers based on demand variability and service level requirements

Master Production Scheduling

The master production schedule (MPS) translates demand into a time-phased production plan:

Planning horizon: Defining the time period covered by the schedule, typically extending from weeks to months depending on lead times
Time buckets: Organizing the schedule into planning periods (daily, weekly, or monthly) appropriate for the production environment
Available-to-promise: Calculating uncommitted production capacity available for new customer orders
Rough-cut capacity planning: Validating that the MPS is achievable given available resources and known constraints
Schedule stability: Balancing responsiveness to demand changes against the disruption caused by schedule changes
Order prioritization: Establishing rules for sequencing orders based on due dates, customer priority, and profitability

Capacity Analysis

Capacity planning ensures manufacturing resources can support production requirements:

Theoretical capacity: Maximum possible output assuming continuous operation without any downtime or losses
Practical capacity: Realistic output accounting for planned maintenance, changeovers, and typical operating conditions
Demonstrated capacity: Actual historical output that reflects real-world performance including all losses
Bottleneck identification: Finding the constraining resources that limit overall system throughput
Load leveling: Smoothing production over time to avoid peaks and valleys in resource utilization
Capacity investment planning: Identifying when additional equipment or personnel will be needed to meet growth projections

Finite and Infinite Scheduling

Different scheduling approaches address different manufacturing environments:

Infinite scheduling: Assumes unlimited capacity and schedules work based solely on required dates, useful for initial planning
Finite scheduling: Considers actual resource availability and sequences work to avoid overloading
Forward scheduling: Starts from material availability and schedules forward to determine completion date
Backward scheduling: Starts from required due date and schedules backward to determine when to start
Constraint-based scheduling: Focuses on bottleneck resources and schedules other operations around them
Dynamic rescheduling: Adjusting schedules in real-time as conditions change during execution

Material Requirements Planning

Material Requirements Planning (MRP) calculates what materials are needed, in what quantities, and when they are required to support the production schedule. MRP logic explodes bills of material, considers existing inventory and open orders, and generates planned orders for procurement and production.

MRP Fundamentals

The core MRP calculation determines material requirements from demand and supply data:

Gross requirements: Total material needed to support the production schedule without considering available supply
Scheduled receipts: Open purchase orders and production orders expected to arrive
Projected available balance: Inventory expected to be on hand at each point in time
Net requirements: Additional material needed after accounting for available inventory and scheduled receipts
Planned order releases: Suggested orders offset by lead time to meet net requirements
Lot sizing: Grouping requirements into economical order quantities

Bill of Materials Management

Accurate bills of material are essential for MRP accuracy:

BOM structure: Organizing parent-child relationships that define product structure
Quantity per: Specifying how many of each component are required per parent assembly
Effectivity dates: Managing engineering changes by specifying when BOM changes take effect
Reference designators: Linking components to specific locations on the circuit board
Phantom assemblies: Representing subassemblies that are not stocked but flow directly to the next level
Alternate components: Identifying approved substitutes when primary components are unavailable

MRP Parameters

Proper parameter settings are critical for MRP performance:

Lead times: Time required to procure or manufacture each item, including queue, setup, run, and move times
Safety stock: Buffer inventory to protect against supply or demand variability
Order modifiers: Minimum order quantities, order multiples, and maximum order sizes that constrain lot sizing
Scrap factors: Expected yield losses that increase gross requirements to ensure sufficient output
Planning time fences: Periods within which automatic schedule changes are restricted
Pegging: Linking requirements to their sources to understand demand origins

MRP II and Advanced Planning

Manufacturing Resource Planning extends MRP to encompass broader business processes:

Capacity requirements planning: Detailed capacity analysis at work center level based on planned orders
Shop floor control: Tracking work order status and managing production execution
Financial integration: Connecting production plans to budgets and financial projections
Simulation and what-if analysis: Evaluating alternative scenarios before committing to plans
Advanced planning and scheduling: Sophisticated optimization algorithms for complex manufacturing environments
Multi-site planning: Coordinating material and capacity across multiple manufacturing locations

Work Order Management

Work orders are the fundamental documents that authorize and track manufacturing activities. Effective work order management ensures materials are available, resources are scheduled, quality requirements are documented, and production progress is tracked.

Work Order Creation and Release

Work order creation translates planned production into executable instructions:

Order documentation: Specifying the product, quantity, due date, and any special instructions
Routing assignment: Defining the sequence of operations and work centers for production
Material allocation: Reserving components and materials for the work order
Release criteria: Verifying that materials are available and capacity exists before releasing to production
Kit preparation: Staging materials at the point of use before production begins
Documentation package: Providing assembly drawings, work instructions, and quality requirements

Work Order Tracking

Real-time tracking provides visibility into production status:

Operation completion: Recording when each manufacturing step is completed
Labor tracking: Capturing actual labor hours spent on production
Material consumption: Recording materials used and any variances from planned quantities
Scrap and rework: Documenting non-conforming production and disposition actions
Work-in-process location: Tracking physical location of orders on the production floor
Estimated completion: Projecting completion dates based on current progress and remaining work

Work Order Costing

Work order costing captures actual production costs for financial reporting and analysis:

Material costs: Actual cost of components and materials consumed
Labor costs: Direct labor hours multiplied by labor rates
Overhead allocation: Applying manufacturing overhead based on predetermined rates
Standard cost variance: Comparing actual costs to standard costs to identify variances
Scrap costs: Capturing the cost of materials and labor lost to non-conforming production
Cost of quality: Tracking rework, inspection, and other quality-related costs

Work Order Completion

Work order completion finalizes production and updates inventory:

Receipt to stock: Adding completed products to finished goods inventory
Backflush: Automatically deducting component inventory based on completed quantities
Close procedures: Verifying all operations complete, costs captured, and documentation archived
Variance analysis: Reviewing any differences between planned and actual results
Serialization: Assigning serial numbers and recording traceability information
Quality records: Linking inspection and test results to the completed lot

Production Line Configuration

Production line configuration determines how manufacturing resources are organized and how work flows through the facility. Proper line design balances throughput, flexibility, quality, and cost considerations to optimize overall manufacturing performance.

Line Layout Strategies

Different layout approaches suit different manufacturing requirements:

Product layout: Equipment arranged in sequence for a specific product or product family, maximizing flow efficiency
Process layout: Similar equipment grouped together, providing flexibility for diverse products
Cellular layout: Equipment grouped into cells that produce families of similar products
Fixed-position layout: Product remains stationary while equipment and personnel move to it, used for large assemblies
Hybrid layouts: Combining layout types to address different products or production volumes
U-shaped cells: Arranging equipment in a U-shape to minimize travel and enable multi-machine operation

Line Balancing

Line balancing distributes work evenly across workstations to maximize efficiency:

Takt time calculation: Determining the pace of production based on customer demand and available production time
Work content analysis: Breaking down operations into individual tasks with measured times
Task assignment: Allocating tasks to workstations while respecting precedence constraints
Balance efficiency: Measuring how evenly work is distributed and identifying idle time
Bottleneck management: Addressing the constraining station that limits overall line throughput
Rebalancing triggers: Recognizing when demand changes or process improvements require line rebalancing

Workstation Design

Individual workstation design affects operator efficiency and product quality:

Ergonomic considerations: Designing stations that minimize operator fatigue and prevent injury
Material presentation: Positioning components and tools for easy access and minimal reaching
Visual management: Using visual aids to guide work sequence and highlight abnormalities
Error proofing: Incorporating poka-yoke devices that prevent common errors
Lighting requirements: Providing appropriate illumination for inspection and assembly tasks
ESD protection: Implementing electrostatic discharge controls at sensitive workstations

Automation Integration

Integrating automated equipment requires careful planning:

Automation selection: Choosing between manual, semi-automated, and fully automated processes based on volume and complexity
Equipment connectivity: Enabling communication between machines for coordinated operation
Buffer management: Sizing buffers between operations to absorb variation and prevent starving or blocking
Changeover design: Incorporating features that enable rapid product changeover
Maintenance access: Ensuring equipment can be maintained without disrupting the entire line
Scalability: Designing lines that can be expanded or modified as production requirements change

Setup Time Reduction Strategies

Setup time, the time required to change from producing one product to another, directly impacts manufacturing flexibility and capacity. Reducing setup time enables smaller production lots, faster response to demand changes, and higher overall equipment utilization.

SMED Methodology

Single-Minute Exchange of Die (SMED) is a systematic approach to setup reduction:

Current state analysis: Documenting all setup activities and their durations through observation and video recording
Internal vs. external separation: Distinguishing tasks that require equipment stoppage from those that can be done while running
Converting internal to external: Finding ways to perform more tasks while the equipment is still producing the previous product
Streamlining internal operations: Reducing the time required for tasks that must be done during equipment downtime
Streamlining external operations: Improving preparation activities performed before the changeover begins
Standardization: Creating consistent procedures that can be performed quickly and reliably

Equipment Design for Quick Changeover

Equipment features can significantly impact changeover time:

Quick-release mechanisms: Replacing bolts and screws with clamps, levers, and other fast-acting fasteners
Standardized interfaces: Using common mounting patterns and connections across tooling
Preset adjustments: Marking or presetting positions to eliminate trial-and-error adjustment
Modular tooling: Using interchangeable modules that can be changed without adjustment
Program storage: Saving and quickly recalling machine programs for different products
Self-centering fixtures: Designing fixtures that automatically align work pieces

Organizational Approaches

Organizational factors strongly influence changeover performance:

Changeover teams: Training dedicated teams that perform changeovers efficiently
Parallel operations: Having multiple operators work simultaneously on different changeover tasks
Preparation checklists: Ensuring all tools, materials, and programs are ready before the changeover begins
Shadow boards: Organizing tools in designated locations for immediate availability
Wheel strategy: Grouping similar products to minimize the number and complexity of changeovers
Practice and timing: Regular practice to maintain skills and tracking of changeover times

SMT Changeover Optimization

Surface mount assembly presents specific changeover challenges:

Feeder setup: Organizing feeders to minimize changeover by keeping common components loaded
Family grouping: Designing product families that share common components and feeder setups
Offline programming: Preparing and verifying machine programs while current production continues
Stencil management: Using stencil storage systems and quick-change stencil holders
Reflow profile libraries: Storing and recalling proven reflow profiles for different products
First article verification: Streamlining first article inspection to minimize startup time

First Article Inspection Procedures

First Article Inspection (FAI) verifies that a manufacturing process can produce conforming products before committing to full production. This critical quality gate prevents the production of large quantities of non-conforming product and validates the manufacturing system.

FAI Requirements and Planning

Effective FAI requires systematic planning and preparation:

Trigger conditions: Defining when FAI is required, such as new product introduction, process changes, or production restart after extended downtime
Scope definition: Determining which characteristics and processes will be verified during FAI
Resource planning: Ensuring inspection equipment, personnel, and time are available for thorough evaluation
Documentation requirements: Preparing forms, checklists, and records needed for FAI documentation
Customer notification: Coordinating with customers who may require witness of FAI or approval before production
Risk assessment: Identifying high-risk areas that require additional attention during FAI

FAI Execution

FAI execution involves comprehensive verification of product and process:

Dimensional verification: Measuring critical dimensions and comparing to drawing specifications
Visual inspection: Examining workmanship quality against IPC or customer standards
Electrical testing: Verifying electrical performance meets specifications
Functional testing: Confirming the product performs its intended function correctly
Material verification: Confirming correct materials and components were used
Process verification: Reviewing that manufacturing processes were performed according to procedures
Traceability verification: Confirming material traceability and documentation are complete

AS9102 First Article Inspection

Aerospace industry FAI follows the AS9102 standard:

Form 1 - Part Number Accountability: Documenting part identification, revision, and inspection status
Form 2 - Product Accountability: Identifying materials, special processes, and functional testing
Form 3 - Characteristic Accountability: Recording actual measurements for all design characteristics
Ballooned drawings: Referencing each characteristic to its location on the drawing
Partial and delta FAI: Addressing situations where only some characteristics require re-verification
FAI reporting: Submitting complete FAI packages to customers for approval

Managing FAI Discrepancies

When FAI reveals non-conformances, systematic resolution is required:

Root cause analysis: Investigating why the discrepancy occurred and identifying corrective actions
Disposition decisions: Determining whether discrepant items can be used, reworked, or must be scrapped
Process corrections: Implementing changes to prevent recurrence in production
Re-inspection requirements: Determining which characteristics must be re-verified after corrections
Customer notification: Communicating discrepancies and corrective actions to customers when required
Documentation: Recording all discrepancies, investigations, and resolutions for future reference

Production Yield Tracking and Improvement

Production yield measures the proportion of products that meet quality requirements without rework. Tracking yield provides insight into process health, identifies improvement opportunities, and enables cost control. Systematic yield improvement directly increases capacity and reduces manufacturing costs.

Yield Metrics

Various yield metrics provide different perspectives on manufacturing performance:

First pass yield (FPY): Percentage of units passing all tests and inspections without any rework
Rolled throughput yield: Product of first pass yields across all process steps, reflecting cumulative process performance
Final yield: Percentage of started units that ultimately ship as good product, including those requiring rework
Defects per unit (DPU): Average number of defects found per unit, useful when units may have multiple defects
Defects per million opportunities (DPMO): Defect rate normalized by the number of opportunities for defects
Yield by operation: First pass yield measured at each process step to identify specific problem areas

Yield Data Collection

Accurate yield tracking requires comprehensive data collection:

Defect logging: Recording all defects found at each inspection point with detailed classification
Location tracking: Identifying where on the product defects occur to enable pattern analysis
Time stamping: Recording when defects are detected to correlate with process conditions
Lot traceability: Linking yield data to specific production lots for analysis
Component traceability: Connecting defects to specific component lots when component quality is suspected
Automated data collection: Using test equipment and MES systems to capture yield data automatically

Yield Analysis Techniques

Analytical techniques transform yield data into actionable insights:

Pareto analysis: Ranking defect types by frequency to focus improvement efforts on the vital few
Trend analysis: Monitoring yield over time to detect deterioration or improvement
Correlation analysis: Identifying relationships between process variables and yield outcomes
Location analysis: Using heat maps and spatial analysis to identify problematic areas
Shift and operator analysis: Comparing yield across different production conditions
Component supplier analysis: Evaluating yield performance by component source

Yield Improvement Methodologies

Systematic methodologies drive sustainable yield improvement:

Six Sigma DMAIC: Define, Measure, Analyze, Improve, Control methodology for structured problem solving
8D problem solving: Eight Discipline approach for team-based root cause analysis and corrective action
Design of experiments: Systematic experimentation to identify optimal process settings
Process capability improvement: Reducing variation to achieve higher Cpk values
Error proofing: Implementing mistake-proofing devices that prevent defects
Preventive maintenance: Maintaining equipment to prevent yield-affecting failures

Cycle Time Optimization

Cycle time is the elapsed time from the start to the completion of a manufacturing process. Reducing cycle time increases throughput, improves customer responsiveness, and reduces work-in-process inventory. Cycle time optimization requires understanding both value-adding activities and the waste that extends production time.

Cycle Time Components

Understanding cycle time elements enables targeted improvement:

Process time: Time during which value-adding work is actually performed on the product
Queue time: Time products wait before processing at each operation
Move time: Time spent transporting products between operations
Setup time: Time required to prepare equipment for production
Inspection time: Time spent on quality verification activities
Wait time: Delays caused by material shortages, equipment problems, or other interruptions

In most manufacturing environments, non-value-adding time significantly exceeds actual process time, creating substantial opportunity for improvement.

Bottleneck Management

The bottleneck operation determines overall system throughput:

Bottleneck identification: Finding the operation with the longest cycle time or highest utilization
Bottleneck protection: Ensuring the bottleneck never waits for material or operators
Bottleneck exploitation: Maximizing utilization of the constraint through reduced downtime and changeovers
Subordination: Scheduling non-bottleneck operations to support bottleneck performance
Bottleneck elevation: Adding capacity to the constraint when other improvements are exhausted
Moving bottleneck: Recognizing that addressing one bottleneck often reveals another

Flow Improvement

Improving material flow reduces queue and move times:

Work-in-process reduction: Limiting WIP to reduce queue times and expose problems
Batch size reduction: Moving smaller quantities to reduce wait time for batch completion
Layout optimization: Arranging operations to minimize transport distance
One-piece flow: Moving individual units through production without batching
Pull systems: Triggering upstream production only when downstream operations need material
FIFO lanes: Ensuring materials flow in first-in, first-out sequence to prevent queue jumping

Cycle Time Measurement

Accurate measurement enables tracking of improvement progress:

Time studies: Observing and recording actual operation times
Timestamp tracking: Recording when products enter and leave each operation
Value stream mapping: Documenting current state and designing future state with improved flow
Lead time tracking: Measuring total time from order to delivery
Takt time monitoring: Comparing actual cycle times to required takt time
OEE measurement: Tracking Overall Equipment Effectiveness to identify losses

Lean Manufacturing Implementation

Lean manufacturing is a production philosophy focused on maximizing value while minimizing waste. Originally developed by Toyota, lean principles have become fundamental to modern electronics manufacturing, driving improvements in quality, cost, and delivery performance.

Lean Principles

Five core principles guide lean implementation:

Value definition: Understanding what customers truly value and are willing to pay for
Value stream identification: Mapping all steps required to deliver value and identifying waste
Flow creation: Making value-creating steps flow without interruption or delay
Pull implementation: Producing only what customers need, when they need it
Perfection pursuit: Continuously improving toward the ideal state of zero waste

Waste Elimination

Lean identifies eight types of waste to be eliminated:

Transportation: Unnecessary movement of materials between operations
Inventory: Excess materials, work-in-process, or finished goods beyond what is needed
Motion: Unnecessary movement of people during work
Waiting: Idle time when work is not being performed
Overproduction: Making more than is needed or making it too soon
Overprocessing: Performing work beyond what adds value for the customer
Defects: Production of non-conforming products requiring rework or scrap
Skills underutilization: Not using people's talents, knowledge, and creativity

Lean Tools and Techniques

Various tools support lean implementation:

5S workplace organization: Sort, Set in order, Shine, Standardize, Sustain for workplace efficiency
Visual management: Making status and abnormalities immediately visible
Standard work: Documenting the current best practice for each operation
Kanban: Pull-based signaling system for material replenishment
Kaizen: Continuous improvement through small, incremental changes
Jidoka: Building quality into processes through automation and error detection
Heijunka: Leveling production to smooth flow and reduce variation
Poka-yoke: Error-proofing devices that prevent mistakes

Lean Implementation Approach

Successful lean implementation requires systematic deployment:

Leadership commitment: Active management support and participation in lean initiatives
Training and education: Building understanding of lean principles throughout the organization
Pilot projects: Starting with focused improvement areas to build experience and demonstrate results
Expansion: Extending lean practices across the organization based on pilot learning
Cultural change: Shifting from firefighting to prevention and continuous improvement
Sustainability: Embedding lean thinking into daily operations and decision-making

Enterprise Resource Planning Integration

Enterprise Resource Planning (ERP) systems integrate production planning with broader business processes including finance, procurement, sales, and human resources. ERP provides the information backbone that enables coordinated decision-making across the organization and supply chain.

ERP Core Functions

ERP systems encompass multiple integrated business functions:

Financial management: General ledger, accounts payable/receivable, and financial reporting
Procurement: Purchase order management, supplier relationships, and receiving
Inventory management: Stock tracking, warehouse management, and inventory control
Production planning: MRP, scheduling, and capacity planning
Order management: Sales orders, pricing, and customer delivery
Human resources: Employee records, payroll, and labor management
Quality management: Non-conformance tracking, corrective actions, and quality records

MES Integration

Manufacturing Execution Systems complement ERP for shop floor control:

Real-time data exchange: Synchronizing work orders, inventory, and production status between systems
Detailed scheduling: MES provides fine-grained scheduling that ERP systems typically cannot support
Production tracking: Capturing detailed production data that feeds back to ERP
Quality data: Recording inspection results and linking to ERP quality management
Traceability: Maintaining detailed genealogy that connects to ERP lot tracking
Labor reporting: Capturing time and attendance data for ERP payroll processing

Supply Chain Integration

ERP enables collaboration with customers and suppliers:

Electronic data interchange: Automated exchange of orders, forecasts, and shipping documents
Supplier portals: Providing suppliers visibility to demand and inventory
Customer portals: Enabling customers to track order status and shipments
Demand visibility: Sharing forecasts and consumption data with supply chain partners
Vendor managed inventory: Allowing suppliers to manage inventory replenishment
Advanced shipping notices: Receiving shipment information before material arrives

ERP Implementation Considerations

Successful ERP implementation requires careful planning:

Requirements definition: Clearly defining business requirements and expected benefits
System selection: Evaluating ERP options against functional requirements and budget
Process standardization: Aligning business processes with ERP best practices
Data migration: Cleansing and converting data from legacy systems
User training: Ensuring users understand how to use the system effectively
Change management: Managing organizational change that accompanies new systems
Continuous improvement: Optimizing system use and adding functionality over time

Industry 4.0 and Smart Manufacturing

Next-generation systems extend ERP with advanced technologies:

Internet of Things: Connected sensors and equipment providing real-time visibility
Artificial intelligence: Machine learning for demand forecasting, quality prediction, and optimization
Digital twin: Virtual models of products and processes for simulation and optimization
Cloud computing: Flexible, scalable infrastructure for manufacturing applications
Advanced analytics: Big data analysis for insights and decision support
Blockchain: Distributed ledger technology for supply chain transparency and traceability

Performance Measurement and Continuous Improvement

Effective production planning and control requires continuous monitoring and improvement. Key performance indicators provide visibility into manufacturing performance, while systematic improvement methodologies drive ongoing enhancement of planning and execution capabilities.

Key Performance Indicators

KPIs measure production planning and control effectiveness:

On-time delivery: Percentage of orders delivered by the committed date
Schedule adherence: Actual production versus planned production
Inventory turns: Annual cost of goods sold divided by average inventory value
Work-in-process days: Average time materials spend in production
Capacity utilization: Actual output versus available capacity
Overall equipment effectiveness: Availability times performance times quality
Cost per unit: Total manufacturing cost divided by units produced
Forecast accuracy: Comparison of demand forecast to actual demand

Continuous Improvement Programs

Structured programs drive sustained improvement:

Daily management: Regular review of performance metrics and response to abnormalities
Kaizen events: Focused improvement activities addressing specific problems or opportunities
Six Sigma projects: Data-driven projects targeting significant performance improvements
Suggestion programs: Systems for capturing and implementing employee improvement ideas
Benchmarking: Learning from best practices within and outside the industry
Technology adoption: Evaluating and implementing new technologies that improve performance

Summary

Production planning and control integrates multiple disciplines to orchestrate manufacturing operations effectively. From demand forecasting and master scheduling through material requirements planning and work order execution, these systems ensure that customer requirements are met while optimizing resource utilization and minimizing costs.

Success in production planning requires both technical competence in planning systems and methodologies, and organizational capability in execution and continuous improvement. The integration of ERP systems, manufacturing execution systems, and lean manufacturing principles provides the foundation for world-class manufacturing performance.

As manufacturing complexity continues to increase and customer expectations for quality, delivery, and flexibility intensify, the importance of effective production planning and control grows correspondingly. Organizations that master these capabilities achieve competitive advantage through superior customer service, lower costs, and the agility to respond to changing market conditions.