Guide to Improving Machine Tool Machining Efficiency: Reducing Waste in 5 Dimensions from Process, Operation to Equipment

In machine tool machining, "low efficiency" is often not due to insufficiently advanced equipment, but rather dragged down by a large amount of hidden waste (such as redundant processes, waiting time, and high rework rates). Many factories seem busy, but the actual effective machining time only accounts for 60%-70% of the machine running time. This article breaks down practical efficiency improvement methods from 5 core dimensions including process optimization, operation standardization, and equipment guarantee, helping you achieve production capacity breakthroughs with existing equipment.

I. Process Optimization: Eliminate Redundant Links to Make Machining "Take Fewer Detours"

1. Optimize Process Sequence: Follow the Principles of "Roughing Before Finishing, Surface Before Hole, Main Before Secondary"

• Roughing Before Finishing: First remove most of the material (roughing), then perform high-precision machining (finishing). For example, when machining shaft parts, first turn the rough outline of the outer circle (leaving 0.1-0.2mm finishing allowance), and finally finish turning to the required size. This avoids the vibration during roughing affecting the finishing precision and reduces secondary machining.

• Surface Before Hole: First machine the plane, then use the plane as a reference to machine the hole system. For instance, when machining box parts, first mill the mounting surface, then drill and bore holes based on this surface. This ensures the perpendicularity and positional accuracy of the holes, avoids dimensional deviations caused by unstable references, and reduces rework.

• Main Before Secondary: Prioritize machining the core functional surfaces of the part (such as bearing mounting holes and mating surfaces), then process non-critical surfaces (such as chamfers and lightening grooves). This prevents processing errors of non-critical surfaces from affecting the precision of critical surfaces. At the same time, after machining the critical surfaces, the processing parameters of non-critical surfaces can be adjusted according to the actual size, reducing scrap.

2. Merge Similar Processes: Reduce Clamping and Waiting Time

• Turn-Mill Compound Machining: For parts requiring both turning and milling (such as shafts with keyways), if the equipment supports it, complete the processing in one clamping on a turn-mill compound machine. This avoids transferring workpieces between lathes and milling machines, reducing clamping and positioning time (usually saving 30%-40% of auxiliary time).

• Multi-Station Simultaneous Machining: Use multi-station fixtures or turret lathes to realize "one clamping, multi-surface machining". For example, when machining flange parts, use an indexing fixture to complete the machining of the end face, outer circle, and bolt holes in one clamping without repeatedly disassembling the workpiece, improving efficiency.

• Centralized Tool Use: When programming machining procedures, concentrate the processes using the same tool to reduce tool change times. For example, when using an end mill to machine multiple planes and grooves, first complete all plane milling, then process all grooves, avoiding frequent tool changes (each tool change takes about 1-2 minutes, and the cumulative waste is significant in mass production).

3. Select Cutting Parameters Reasonably: Balance "Efficiency" and "Quality"

• Pursue "Speed" in Roughing: Prioritize increasing the depth of cut (removing more material at one time) and feed rate, and appropriately reduce the cutting speed to shorten roughing time. For example, when machining 45# steel with cemented carbide tools, the depth of cut can be set to 2-5mm, feed rate to 0.2-0.5mm/r, and cutting speed to 80-100m/min during roughing.

• Pursue "Stability" in Finishing: Increase the cutting speed and reduce the feed rate to ensure surface quality. Taking the finishing of 45# steel as an example, set the depth of cut to 0.1-0.3mm, feed rate to 0.05-0.1mm/r, and cutting speed to 120-150m/min, balancing efficiency and precision.

• Use "High-Speed Cutting" Technology: If the equipment rigidity is sufficient (such as a vertical machining center with spindle power ≥7.5kW), high-speed cutting can be adopted (cutting speed is 50%-100% higher than conventional). It is especially suitable for soft materials such as aluminum alloys and plastics. The machining efficiency can be improved by more than 2 times, and the surface roughness is better (Ra≤1.6μm), reducing subsequent polishing processes.

II. Operation Standardization: Reduce Human Errors to Make Every Minute "Effective"

1. Fast Tool Setting: Master the Skills of "Unified Datum" and "Auxiliary Tools"

• Unified Datum Principle: Use the same datum (such as one end face and outer circle of the part) for all processes to avoid re-alignment during each tool setting. For example, when machining shaft parts, use one end face as the axial datum and the outer circle as the radial datum. Subsequent processes all use this as the reference for tool setting, reducing positioning errors and tool setting time.

• Use Efficient Tool Setting Tools: Replace the trial cutting method with an edge finder for tool setting, which only takes 2-3 minutes to locate the X and Y axis datums of the part. Use a tool presetter to measure tool length and radius with an accuracy of ±0.001mm, and no need to pause for measurement during machining, saving 50% of time compared with manual tool setting.

• Save Tool Setting Data: Save the tool setting parameters (tool length compensation, radius compensation) of commonly used parts in the machine tool memory. When machining next time, call them directly without re-tool setting (especially suitable for multi-variety, small-batch production).

2. Program Debugging: "Segmented Verification + Simulation Operation" Reduce Trial Cutting Waste

• Segmented Programming and Verification: Compile the machining program of complex parts into "roughing segment", "finishing segment", and "chamfering segment". After compiling each segment, run the simulation separately to confirm no interference before merging, avoiding the entire program being scrapped due to one segment error.

• Machine Simulation Operation: After calling the program, first turn off the spindle and coolant, start the "dry run", and observe whether the tool path is consistent with the part model (through the 3D simulation function of the machine tool display). Focus on checking for interference at corners and deep cavities. Only after confirmation, clamp the workpiece for trial cutting.

• "Light" Trial Cutting for the First Part: When trial cutting the first part, reduce the cutting parameters by 20% (especially the feed rate), and manually control the feed rate (start with 25%-50% rate) to observe the cutting status. Only after confirming the size is qualified, restore the normal parameters for mass production.

3. On-Site Management: "Real-Time Cleaning + Material Return" Avoid Waiting

• Real-Time Chip Cleaning: After processing a batch of parts (or every 2 hours), clean the chips on the worktable and guideways with compressed air or a shovel. Avoid chips jamming the guideways or affecting workpiece clamping (especially when machining cast iron and aluminum alloys, chips are easy to accumulate).

• Fixed-Point Material Storage: Place unprocessed workpieces, processed workpieces, tools, and fixtures in designated areas (distinguished by signs) to avoid searching for materials during machining. For example, set up an "unprocessed area" (for 3-5 batches of unprocessed workpieces) and an "inspected area" (for qualified parts) next to the machine tool to reduce the time for fetching materials back and forth.

• Prepare Auxiliary Materials in Advance: Check whether the coolant, lubricating oil, and tools are sufficient before machining. Avoid shutdown due to lack of materials during machining (for example, replace worn tools with new ones in advance, and replenish coolant in time when it is insufficient).

III. Equipment Guarantee: Reduce Fault Downtime to Make Equipment Run "At Full Load"

1. Do Not Neglect Daily Maintenance: Perform Basic Maintenance on Schedule

• Daily Inspection: Before starting the machine, check the lubrication system (oil level, oil pressure), cooling system (liquid level, leakage), and safety protection (protective cover, emergency stop button) to avoid equipment abnormalities due to lack of oil or water leakage.

• Weekly Inspection: Clean the chips on the guideways and ball screws, and check whether the guideway lubrication is uniform; inspect the tool magazine and tool change mechanism to ensure the tool holders are not loose and there is no jamming during tool change.

• Monthly Inspection: Measure the spindle radial runout and worktable flatness, and adjust the precision deviation in time; check the electrical system and clean the dust in the distribution box to avoid system alarms due to poor heat dissipation.

2. Deal with "Small Problems" in Time: Avoid Fault "Expansion"

• Identify Abnormal Signals: During machining, if "the spindle temperature is too high (exceeding 40℃)", "cutting vibration is obvious", or "part size fluctuation exceeds ±0.01mm", stop the machine immediately for inspection. This may be caused by lack of oil in the guideways, tool wear, or loose spindle bearings.

• Troubleshoot Simple Faults by Yourself: For example, if the machine alarms "insufficient lubrication", first check the oil level in the oil tank. If the oil level is normal, then check whether the lubrication pump motor is working and whether the oil pipe is blocked (simple faults can be solved within 10-20 minutes, avoiding time waste waiting for maintenance personnel).

• Establish Fault Records: Record the "phenomenon, cause, handling method, and downtime" of each equipment failure, and analyze them regularly (such as counting fault types monthly) to make targeted improvements (for example, if tool wear occurs frequently, optimize cutting parameters or replace more wear-resistant tools).

3. Arrange "Downtime" Reasonably: Off-Peak Maintenance and Repair

• Off-Peak Maintenance: Arrange weekly maintenance 1 hour before off work on Friday to complete guideway cleaning, lubricating oil replenishment, and other work without occupying normal production time from Monday to Friday.

• Planned Maintenance: According to the equipment service life and manual, plan the replacement time of 易损 parts (such as spindle bearings, guideway protective covers, and sealing rings) in advance. After the equipment has been running for the specified time (such as 5000 hours of spindle operation), use weekends to stop the machine for replacement to avoid sudden failures.

IV. Tool Management: Select and Use Tools Properly to Reduce "Ineffective Cutting"

1. "Adaptable" Tool Selection: Avoid "Over-Engineering" or "Under-Engineering"

• Choose "Durable" Tools for Roughing: The focus of roughing is impact resistance and wear resistance. Cemented carbide brazed tools (low cost) or coated cemented carbide tools (such as TiCN coating, whose wear resistance is twice that of ordinary cemented carbide) can be selected.

• Choose "High-Precision" Tools for Finishing: Finishing requires ensuring surface quality and dimensional accuracy. Superhard tools (such as CBN tools for machining hardened steel) or high-precision indexable inserts (runout ≤0.005mm) should be used.

• Choose "Special" Tools for Deep Hole and Narrow Slot Machining: Use deep hole drills with internal cooling channels for deep hole machining (smooth chip evacuation, avoiding chip blockage), and ultra-thin end mills for narrow slot machining (width matching the slot width, forming in one cut, avoiding multiple cuts).

2. "Controllable" Tool Life: Avoid "Premature Replacement" or "Overuse"

• Set Life Parameters: According to the tool material and processed material, set the tool service life (for example, when a cemented carbide turning tool processes 45# steel, the life is set to processing 200 parts or cutting for 3 hours). Replace the tool in time after reaching the service life to avoid precision degradation caused by tool wear.

• Adopt "Tool Presetting": Measure the length and radius of the backup tool on the tool presetter in advance, and set the compensation parameters. When the tool in use reaches the service life, the backup tool can be replaced quickly, reducing the downtime for tool change from 5-10 minutes to 1-2 minutes.

• "Qualified" Regrinded Tools: After regrinding regrindable tools (such as HSS drills), check the sharpness of the cutting edge, angle error (side cutting edge angle and rake angle error ≤±1°), and runout (≤0.01mm). Ensure the performance of the reground tool is close to that of a new tool, avoiding reduced machining efficiency due to unqualified regrinding.

V. Quality Control: Reduce Rework and Scrap to Make "Every Piece Qualified"

1. Strict "First Article Inspection": Prevent Mass Scrap

• Full-Size Inspection: The first article needs to inspect all key dimensions (such as hole diameter, tolerance, and surface roughness) and geometric tolerances (such as perpendicularity and parallelism), rather than only part of the dimensions (for example, when machining shaft parts, it is necessary to inspect the outer diameter, step length, keyway depth, coaxiality, etc.).

• Simulated Assembly Inspection: For parts with assembly requirements (such as bearing seats), the first article should be assembled with matching parts (such as bearings) to check whether the assembly clearance and interference meet the requirements, avoiding assembly difficulties caused by dimensional deviations.

• Recording and Traceability: Record the first article inspection results in the "First Article Inspection Form", indicating "inspection date, inspector, and qualification status". If unqualified, analyze the reasons (such as program errors and tool wear), rectify, and re-trial cut until the first article is qualified.

2. Timely "In-Process Inspection": Detect Problems Early

• Key Dimension Sampling Inspection: During the inspection, focus on detecting easily fluctuating dimensions (such as deep hole depth and thin-walled part thickness). Measure quickly with calipers, micrometers, or dial indicators. When the size is out of tolerance (close to the upper or lower tolerance limit), adjust the cutting parameters or replace the tool in time.

• Observe Machining Status: During the inspection, pay attention to the cutting sound (whether there is abnormal noise), chip shape (whether it is normally curled without fragmentation or adhesion), and workpiece surface quality (whether there are chatter marks and burrs). These phenomena are often precursors to size out-of-tolerance.

3. Decisive "Abnormal Handling": Avoid Problem Expansion

• Analyze the Reasons: Quickly check the reasons for disqualification, whether it is "equipment problems" (such as increased spindle runout), "tool problems" (such as cutting edge wear), or "operation problems" (such as tool setting errors).

• Rectify in Time: Take measures according to the reasons (such as replacing spindle bearings, regrinding tools, and re-tool setting). After rectification, reprocess the first article, and continue production only after the inspection is qualified. Avoid processing with problems leading to more scrap.

Conclusion: The Core of Efficiency Improvement is "Reducing Waste"