SMED for Deep Hole Drilling: Reducing Changeover Time Between Jobs

A hydraulic cylinder manufacturer operating four BTA deep hole drilling machines in a German production facility faced a persistent OEE bottleneck: job changeovers between different bore diameters required an average of 87 minutes of machine downtime. Tooling change involved removing the existing drill guide assembly, swapping the drill head, replacing the guide bush and support bush, and re-establishing concentricity alignment — a process that consumed 34 minutes alone. Coolant system reconfiguration — changing pressure settings, swapping filtration media, and flushing the system for different bore diameters — added another 22 minutes. Fixture changeover, including swapping collets and adjusting steady rests for different workpiece diameters, took 19 minutes. The remaining 12 minutes were consumed by quality verification — cutting a test piece, measuring bore diameter and straightness, and adjusting offsets. After implementing a structured SMED program over 14 weeks — starting with video analysis of every changeover step, classifying each activity as internal (machine must be stopped) or external (can be done while machine is running), converting 14 internal activities to external, and streamlining remaining internal steps through parallel operations and quick-release mechanisms — the total changeover time was reduced to 11 minutes. The 87% reduction in changeover downtime added 8.3 hours of weekly machine running time, improved OEE from 62% to 74%, and reduced economic batch sizes — enabling smaller lot production and lower work-in-progress inventory valued at €47,000.

SMED Methodology and Its Application to Deep Hole Drilling Machines ​

Single Minute Exchange of Die (SMED) is a systematic methodology for reducing machine changeover time, developed by Shigeo Shingo over a 19-year period at Toyota Motor Company. The "single minute" designation refers to changeover times measured in single-digit minutes (under 10 minutes), not that every changeover must be completed in precisely one minute. The methodology rests on three fundamental distinctions: between internal setup (activities that require the machine to be stopped, such as removing a drill head) and external setup (activities that can be performed while the machine is running, such as pre-staging tooling for the next job); between actual setup work and wasted motion (searching for tools, walking to obtain components, waiting for crane availability); and between sequential operations (one person performing tasks in sequence) and parallel operations (two people working simultaneously on independent tasks).

Deep hole drilling machines present unique SMED challenges compared to standard machining centers. The interconnected nature of the drilling system means that changing from one bore diameter to another affects not just the cutting tool but the entire machine configuration — guide bush diameter, drill tube diameter, coolant pressure and flow requirements, chip evacuation characteristics, and steady rest positioning all change simultaneously. The table below summarizes the primary changeover subsystems on a typical BTA or gun drilling machine and their SMED classification.

The Five Stages of SMED Implementation ​

SMED implementation follows five sequential stages, each building on the previous. Stage one — observation and measurement — involves filming several complete changeovers, breaking each into individual elements (typically 10–30 elements per changeover), timing each element, and recording distances traveled, tools used, and delays encountered. For deep hole drilling changeovers, this video analysis typically reveals that 30–40% of total changeover time is consumed by walking, searching, waiting, and other non-value-added activities rather than the physical work of changing tooling.

Stage two — separating internal and external setup — requires the SMED team to classify every changeover element as internal (I), external (E), or unclear. A critical discipline at this stage is developing a setup checklist that distinguishes between activities that genuinely require the machine stopped and those that are performed during stopped time simply out of habit. Common classification errors in deep hole drilling include: cleaning the guide bush during stopped time (external — can be done after removal while the machine runs), fetching the next drill head from the tool crib (external), adjusting coolant pressure during stopped time (external — if pressure values are known in advance and can be set without test cuts), and measuring the test piece bore diameter during stopped time (external — measurement can occur while the next part is being loaded).

Stage three — converting internal setup to external — is the heart of SMED and typically yields the largest time reductions. For deep hole drilling, the most impactful conversions include: pre-assembling drill heads onto drill tubes offline using a dedicated assembly fixture so that the changeover on the machine involves only a bolted flange connection rather than setting carbide tip protrusion and torqueing retention screws; pre-setting guide bush concentricity on a bench fixture using a dial indicator so that the bush drops into a pre-aligned holder rather than requiring in-machine alignment; pre-setting steady rest positions using a setup gauge or workpiece surrogate so that adjustments are limited to a single clamp; and pre-calculating offset values based on known tool geometry for the specific job, stored in the machine control or a setup sheet, eliminating the test-cut-and-measure cycle.

Stage four — streamlining internal setup — focuses on reducing the time required for activities that must remain internal (machine stopped). Key techniques for deep hole drilling include: replacing bolted flange connections with quick-release clamps on drill guide housings; replacing threaded collet retainers with hydraulic or pneumatic clamping systems; installing guide bush holders that accept the bush with a bayonet mount rather than threaded ring; using powered steady rest adjustment instead of manual screw adjustment; and implementing single-motion locking mechanisms for drill tube support bushes. Tool standardization also contributes significantly — reducing the number of different bolt sizes, wrench types, and adjustment mechanisms across the machine reduces tool-changing time during changeover.

Stage five — streamlining external setup — addresses the efficiency of activities performed while the machine is running. This includes: organizing the changeover tool cart with dedicated locations for each job's tooling, organized by changeover sequence; implementing shadow boards and visual management for changeover tools; staging all components in the correct sequence before the machine stops; and developing standardized changeover work instructions with time targets for each element. In deep hole drilling environments, this stage often reveals opportunities to prepare coolant condition (pre-heating or pre-cooling to operating temperature, pre-mixing emulsion concentrations) and to pre-position workpiece handling equipment such as cranes, conveyors, or robotic grippers.

SMED Implementation Roadmap and Performance Metrics ​

Implementing SMED on deep hole drilling machines follows a structured project timeline spanning 10–16 weeks. The implementation begins with a baseline measurement phase (weeks 1–2) during which the SMED team films 4–6 changeovers across different job transitions (small-to-large bore diameter, large-to-small diameter, same diameter but different workpiece length, and material changeovers such as steel to cast iron). The video analysis is used to create a spaghetti diagram of operator movement, a detailed element-by-element time breakdown, and an initial internal/external classification.

Weeks 3–5 focus on external conversion and tooling preparation. The team designs and fabricates quick-change fixtures, pre-set tooling carts, and external setup stations. For deep hole drilling, this phase often requires designing dedicated drill head pre-assembly fixtures that replicate the interface geometry of the machine spindle so that drill head runout can be verified offline. Guide bush pre-setting fixtures with dial indicators and master arbors are built, and steady rest position set-points are documented for each job family. The coolant system is analyzed for opportunities to install quick-connect hose fittings, divert valves for rapid coolant type switching, and pre-set pressure regulator stations.

Weeks 6–8 implement physical changes to the machine and work area. Quick-release mechanisms are installed on the drill guide housing, collet chuck, and steady rests. Shadow boards and tool carts are built and populated. Coolant system modifications are completed. Standard work instructions for the new changeover procedure are drafted. During this phase, operators are trained on the new procedures and the rationale behind each change — operator buy-in is critical for SMED success, and operators who understand why they are changing their methods are more likely to adopt and improve upon the new procedures.

Weeks 9–12 are the transition phase during which the new changeover procedure is piloted, refined, and stabilized. Each changeover is timed and reviewed, and the team makes incremental adjustments to tool cart layouts, procedure sequences, and fixture designs based on operator feedback. By week 12, the target changeover time should be achieved or closely approached.

The table below presents typical SMED results from deep hole drilling changeover reduction projects across different machine types and job families.

SMED Metrics Beyond Changeover Time ​

While total changeover time is the primary SMED metric, several secondary metrics provide deeper insight into the effectiveness of the implementation. Internal setup time — the time the machine is actually stopped — is the most critical measure because it directly affects OEE Availability. SMED projects on deep hole drilling machines typically reduce internal setup time from 70–85% of total changeover time to 40–55%, as more activities are successfully converted to external or parallel execution.

Repeatability of changeover time — measured as the standard deviation of changeover times across multiple job transitions — is an important indicator of process stability. A well-implemented SMED system should achieve a coefficient of variation (CV) under 15%, meaning that changeover times are consistent and predictable. High variability typically indicates that setup conditions (tooling availability, operator skill, machine condition) are not sufficiently standardized.

First-part quality after changeover is a critical SMED outcome measure. One risk of aggressive changeover reduction is that the first part after changeover fails quality inspection because of incorrect setup. Tracking first-pass yield (FPY) on the first three parts after each changeover provides an early warning of SMED problems — a decline in post-changeover FPY indicates that external preparation is not adequately replicating the precision achieved through in-machine setup. In well-designed SMED systems for deep hole drilling, first-part FPY should remain above 95%, with bore diameter within ±0.025 mm of target and straightness within 0.05 mm per 100 mm of bore length.

Economic Impact and Batch Size Implications ​

The reduction in changeover time enabled by SMED has a direct and substantial impact on production economics. The classic economic batch quantity (EBQ) formula — in which optimal batch size is proportional to the square root of changeover cost — means that reducing changeover time by 87% (as in the hydraulic cylinder manufacturer case) reduces the optimal batch size by approximately 64%. This reduction in minimum economic batch size enables manufacturers to run smaller lots more frequently, reducing work-in-progress (WIP) inventory, finished goods inventory, and response time to customer orders.

For deep hole drilling operations specializing in custom hydraulic cylinders, oilfield components, or aerospace structural parts — where job quantities of 5–50 pieces are common — the ability to economically run smaller batches is critical. Before SMED, the 87-minute changeover time on BTA machines forced production planners to batch similar jobs together, creating weeks of WIP inventory and extended lead times. After SMED reduced changeover to 11 minutes, the same machines could economically run single-shift lots of individual customer orders, reducing average WIP from 320 pieces to 95 pieces and average lead time from 22 working days to 8 working days.

The financial impact extends beyond inventory reduction. The 8.3 hours per week of recovered machine time on each of four machines (33.2 hours total per week) represented approximately €285,000 per year in additional available capacity without capital expenditure — equivalent to adding a fifth BTA machine at a fraction of the cost (SMED implementation costs, including fixture design, quick-change hardware, and project labor, totaled approximately €38,000 per machine). When capacity is constrained, SMED effectively creates capacity. When capacity is not constrained, SMED enables smaller batches and faster response.

FAQ ​

What is the difference between internal and external setup in SMED? ​

Internal setup refers to activities that can only be performed while the machine is stopped, such as physically removing a drill head from the spindle, changing a guide bush, or swapping a collet. External setup refers to activities that can be performed while the machine is still running the previous job, including staging tools for the next job, pre-assembling drill heads on a bench, pre-setting guide bush concentricity on a fixture, cleaning tools and fixtures, pre-heating or pre-conditioning coolant, and reviewing the next job's setup sheet. The primary discipline in SMED is rigorously separating these two categories — most deep hole drilling changeovers initially contain significant internal setup time that could be converted to external with proper preparation and organization.

How does SMED apply to a gun drilling machine specifically? ​

Gun drilling changeovers typically involve fewer subsystems than BTA machines because gun drilling uses smaller bore diameters (1–40 mm) and simpler tooling. The primary SMED opportunities on gun drilling machines are: collet changeover for different workpiece diameters (converting to quick-change collet systems); drill guide bushing changeover (using preset bushing holders); drill tube and drill head changeover (pre-assembling drill head to tube on a bench fixture); steady rest adjustment (presetting using gauge blocks or workpiece surrogate); and coolant pressure adjustment (using a pre-set digital pressure regulator with job recall). Typical baseline changeover times of 35–50 minutes on gun drilling machines can be reduced to 5–8 minutes through SMED.

Can SMED be applied to CNC deep hole drilling machines with automatic tool changers? ​

Yes, but the SMED focus shifts from tool-changing to the peripheral setup activities that automatic tool changers do not address. On CNC deep hole drilling machines with automatic tool changers (ATC), the drill head change itself may already be fast (30–60 seconds), but the overall changeover still includes: workpiece fixturing changeover (collet or chuck jaw change); drill guide bushing change (if the machine uses interchangeable guide bushes); coolant system reconfiguration (pressure, flow, and filtration changes for different bore diameters); steady rest adjustment; chip conveyor configuration; and program selection and verification. The SMED analysis on CNC deep hole drilling machines often reveals that the tool change time is a small fraction of total changeover time, and the largest gains come from fixture changeover and coolant system reconfiguration.

What tools and equipment are needed to implement SMED on deep hole drilling machines? ​

The primary SMED tools and equipment include: a video camera for changeover observation and analysis (any smartphone with time-lapse capability suffices); a changeover analysis board or software for element-by-element timing and classification; pre-set tooling carts with dedicated job-specific tooling organized by changeover sequence (typically 3–5 carts per machine for different job families); bench fixtures for pre-setting guide bush concentricity and drill head runout (costing $500–$2,000 each depending on precision requirements); quick-change mechanical hardware such as bayonet-mount guide bush holders, quick-release clamps for drill guide housings, hydraulic collet chucks, and pneumatic steady rest clamps; standardized work instructions with time targets for each changeover element; and shadow boards with organized changeover tools (wrenches, indicating gauges, cleaning materials) labeled and located within arm's reach of the machine.

What are the most common mistakes in SMED implementation for deep hole drilling? ​

The most common mistake is attempting to streamline internal setup activities without first rigorously separating internal and external activities — applying quick-release clamps and hydraulic systems to activities that should have been converted to external setup in the first place. The second most common mistake is implementing SMED as a one-time project rather than an ongoing improvement process — the initial improvement creates momentum, but sustaining and further reducing changeover time requires regular review of changeover video, fresh analysis of every element, and continuous refinement of procedures. The third mistake is neglecting operator involvement — SMED changes that are designed by engineers and imposed on operators typically fail within weeks as operators revert to familiar methods. The most successful deep hole drilling SMED implementations invest significant time in operator training and empowerment, making operators the owners of the changeover process. The fourth mistake is focusing exclusively on tooling changeover while ignoring fixture changeover, coolant system reconfiguration, and quality verification activities — these three areas together typically consume 50–60% of total changeover time in deep hole drilling.

Disclaimer: The changeover time reductions, OEE improvements, and financial figures presented in this article are based on published case studies and industry-reported SMED implementation results for deep hole drilling operations. Actual results depend on machine condition, operator skill, job complexity, product mix, organizational commitment to lean manufacturing principles, and the specific SMED methods and tools implemented. No guarantee of specific changeover time reduction or financial return is expressed or implied. Deep hole drilling equipment modifications for SMED should be reviewed by the machine manufacturer or a qualified machine tool engineer to ensure that quick-change mechanisms and pre-set tooling fixturing maintain the required precision, rigidity, and safety characteristics for deep hole drilling operations. All data is provided for informational purposes and reflects industry practices as of 2026.