Auto-Sector Interview Preparation

Lean manufacturing maximises customer value while minimising waste. It focuses on eliminating the eight wastes, smooth flow, pull-based production, and continuous improvement (kaizen). Originating from the Toyota Production System, it improves quality, cost, and delivery simultaneously.

Defects, Overproduction, Waiting, Non-utilised talent, Transportation, Inventory, Motion, and Excess processing — remembered by 'DOWNTIME'. Identifying and eliminating these wastes is central to lean improvement.

JIT produces and delivers parts exactly when needed, in the quantity needed — minimising inventory and its associated cost and waste. It relies on stable demand, reliable suppliers, quick changeovers, and pull signals (kanban). It exposes problems quickly but needs robust processes.

Kanban is a visual pull-based scheduling system that signals when to produce or replenish — traditionally using cards. A downstream process consuming parts triggers an upstream process to make more, preventing overproduction and controlling work-in-progress.

Push production makes goods based on forecasts and pushes them downstream regardless of actual demand (risks overproduction/inventory). Pull production makes goods only in response to actual downstream demand (kanban signals), reducing inventory and matching output to need.

Takt time is the rate at which products must be made to meet customer demand — calculated as available production time ÷ customer demand. It sets the production pace; cycle time must be at or below takt time to keep up without overproducing.

Cycle time is how long one unit takes to complete at a process. Lead time is total elapsed time from order to delivery (including waiting). Takt time is the customer demand pace. Ideal flow has cycle time ≤ takt time, and lead time minimised.

5S is a workplace organisation method: Sort (remove unneeded items), Set in order (a place for everything), Shine (clean and inspect), Standardise (consistent practices), and Sustain (maintain discipline). It improves efficiency, safety, and quality, and is the foundation for other lean tools.

TPM aims for maximum equipment effectiveness through proactive and preventive maintenance involving all employees, including operators (autonomous maintenance). Its goals are zero breakdowns, zero defects, and zero accidents, often measured by OEE.

OEE (Overall Equipment Effectiveness) measures how effectively equipment is used: OEE = Availability × Performance × Quality. Availability accounts for downtime, Performance for speed losses, Quality for defects. World-class OEE is around 85%.

SMED (Single-Minute Exchange of Die) is a method to drastically reduce changeover/setup time (ideally under 10 minutes) by converting internal setup steps (done while stopped) into external ones (done while running) and streamlining the rest. It enables smaller batches and more flexibility.

Kaizen means continuous improvement through small, incremental changes involving everyone. Rather than big one-off projects, it builds a culture where employees regularly identify and implement improvements in their own work areas — compounding into significant gains.

A bottleneck is the process step with the least capacity, limiting overall throughput. Manage it by the Theory of Constraints: identify it, exploit it (maximise its utilisation), subordinate other processes to it, elevate its capacity, then repeat as the bottleneck shifts.

Preventive maintenance is scheduled at fixed intervals regardless of condition. Predictive maintenance uses condition monitoring (vibration, temperature, oil analysis) to predict failures and intervene only when needed — reducing unnecessary work and unexpected breakdowns.

Gemba ('the real place') walk is when managers go to the actual work area to observe processes, ask questions, and understand reality firsthand — rather than relying on reports. It surfaces problems, shows respect for workers, and supports informed improvement.

Heijunka levels production by volume and product mix over a period, rather than building to fluctuating orders. It smooths workload, reduces inventory and lead time, and enables a steady, predictable flow — a key enabler of JIT.

Ensuring production targets, quality, and safety are met. Responsibilities include manpower planning and allocation, monitoring output and OEE, addressing line stoppages, enforcing standards and 5S, coordinating with maintenance/quality/logistics, and developing the team.

Standardised work documents the current best, safest, most efficient method to perform a task — including sequence, timing, and standard inventory. It ensures consistency, forms the baseline for improvement (you can't improve an unstable process), and speeds training.

Jidoka ('automation with a human touch') means equipment automatically detects abnormalities and stops, preventing defects from passing downstream and alerting operators. It builds quality into the process and lets one operator oversee multiple machines.

Quickly go to the line (Gemba), identify whether it's a machine, material, manpower, or method issue. Check for breakdowns, material shortages, quality holds, or absenteeism. Apply interim containment to restore flow, then root-cause the issue and implement a permanent countermeasure.