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In the fast-paced world of precision CNC parts manufacturing, efficiency drives success. Recently, a valued client approached us with a straightforward yet critical request: custom rectangular flat bars requiring two through-drilled round holes, surface engraving for identification on one side, and a black oxide finish for enhanced corrosion resistance and aesthetics. With an annual demand of 3,000 to 6,000 pieces, the client sought a reliable OEM partner to deliver consistent quality and timely production. Our engineering team evaluated the project, comparing traditional CNC milling against an innovative powder metallurgy (PM) approach. The analysis revealed a clear winner: powder metallurgy offered significant advantages in scalability and efficiency. This case study dives into the comparison, showcasing how powder metallurgy can transform high-volume part production for businesses like yours.   The Challenge: Balancing Efficiency, Speed, and Quality in High-Volume Production The flat bar’s simple design—drilling two holes, engraving text, and applying black oxide—belied its manufacturing challenges at scale. Traditional CNC milling, while effective for prototypes or small runs, faces hurdles for mid-to-high volumes like 3,000–6,000 pieces annually. Key challenges include: Material and Setup Inefficiencies Milling starts with oversized stock, generating significant scrap. Each setup demands precise fixturing, increasing labor and machine time. Extended Production Timelines Processing large batches sequentially on CNC mills stretches lead times, delaying deliveries and tying up inventory. Quality Variability While CNC milling offers precision, tool wear or operator inconsistencies can affect hole accuracy, engraving clarity, potentially increasing rework. Powder metallurgy (PM), by contrast, compacts metal powders into near-net-shape molds, sinters them for strength, and requires minimal secondary operations. Our engineers proposed custom PM tooling, arguing it could outperform milling across all metrics for this volume.     Flat bar made by Powder Metallurgy with letter engraving and black oxide finish     Head-to-Head Comparison: Powder Metallurgy vs. CNC Milling Let’s examine the two methods across efficiency, production timeline, and quality for the client’s demand. 1.) Efficiency Analysis CNC Milling Requires no upfront tooling investment, making it initially appealing. However, per-piece efforts—machining raw stock, drilling, engraving, and finishing—accumulate significant time and resources. Material waste further compounds inefficiencies, especially at higher volumes. Powder Metallurgy Involves an initial investment in custom tooling, but this is quickly offset by streamlined production. Near-net-shape forming minimizes waste, and batch sintering integrates drilling and engraving into the mold, reducing secondary operations. The black oxide finish integrates seamlessly with PM post-processing. ⇒ PM delivers substantial efficiency gains, with the tooling investment recouped swiftly through high-volume production.   2.) Production Timeline CNC Milling Large batches extend lead times to weeks, as parts are machined individually or in small groups. Rush orders further complicate schedules. Powder Metallurgy Tooling development takes a few weeks initially, but subsequent production is rapid. Thousands of parts can be compacted and sintered in days, enabling just-in-time delivery and lean inventory management. ⇒ PM cuts lead times dramatically, offering agility for dynamic supply chains.   3.) Quality and Consistency CNC Milling Achieves tight tolerances (±0.01 mm) and clear engravings, but tool degradation can introduce variability, leading to occasional defects. Black oxide adhesion may vary on machined surfaces. Powder Metallurgy Ensures uniform density and strength through controlled sintering. Holes and engravings are molded directly, eliminating variability. Black oxide bonds exceptionally well to PM surfaces, enhancing durability. Tolerances match milling (±0.05 mm standard, tighter with minimal secondary ops), with defect rates near zero. ⇒ PM provides superior consistency and reliability, minimizing rejects and ensuring quality for identification-critical parts.   Switching to Powder Metallurgy for Optimal Results Our team recommended powder metallurgy for the client’s flat bars. The custom mold incorporated the two holes and engraving features upfront, eliminating most secondary machining. Post-sintering, a quick black oxide dip completed the process. After client approval, production began with a prototype run to validate specifications. This switch exceeded expectations, proving powder metallurgy’s superiority for simple, high-volume geometries. If your business produces custom metal components—like flat bars, brackets, or gears—and faces challenges in efficiency, speed, or quality, powder metallurgy could be your solution. Compared to traditional CNC milling, it offers unmatched scalability and consistency for mid-to-high volumes, as demonstrated in this case. Ready to transform your production? Share your OEM needs—part specifications, volumes, or materials—and we’ll provide a tailored solution to optimize your process. Contact us today at sales@apporo-cnc.com to explore how we can elevate your manufacturing efficiency! ...

Recently, a client of mechanical assemblies for machinery applications contact us for a custom iron square tube bushings to serve as spacers for elevating component thickness. Each bushing measured 10.0 mm x 10.0 mm in cross-section (length and width), 10.0 mm in height, and 1.0 mm wall thickness, forming a hollow square profile suitable for load-bearing and alignment purposes. Initially, the production approach involved sourcing standard 3-meter-long iron square tubes (already matching the 10.0 mm x 10.0 mm dimensions) from material suppliers. These were then processed as follows: 1.) Wire EDM (electrical discharge machining) to fabricate custom CNC lathe fixtures for secure holding. 2.) CNC Automatic lathe operations to clamp the square tube and cut it to the precise 10.0 mm height. 3.) Deburrs, oiling and packaging   This method was selected for its apparent simplicity and low material costs, leveraging readily available stock to minimize custom fabrication. However, during initial testing, our engineering team identified critical defects in the lathe-cut edges. The parting tool on the automatic lathe left burrs—small, raised metal protrusions—along the hole edges of the square profile. These burrs compromised the bushing's performance by potentially causing misalignment, wear on mating parts, or interference during insertion into assemblies.     Burrs found inside inner tube     Below shows the way our team look for mitigating the burrs: 1.) Secondary Lathe Refinement Clamping the cut face in the lathe's tailstock (back spindle) and using a drill bit to deburr the opposite hole edge only addressed the boundary of a circle. The sharp corners of the square profile remained inaccessible to the drill, necessitating manual filing consequently. This labor-intensive step not only increased cycle times but also required an additional set of customized square fixtures for the tailstock—fabricated via costly wire EDM—adding significant setup expenses. 2.) Tumbling Introducing a tumbling process with abrasive media was considered to automate deburring. However, tests showed it was ineffective for the thin-walled geometry; instead of removing burrs, the abrasive media compressed them inward, reducing the internal square hole width below tolerances (e.g., from 8.0 mm to 7.6 mm or less). This distortion risked functional failures, such as binding in the assembly.   The production approach above, while feasible for low volumes, proved inefficient and unreliable at scale, potentially inflating the costs due to rework and risk of scrap.   Transition to Powder Metallurgy Considering an annual demand of 6,000-10,000 pieces of this bushing, also based on Apporo's decades of accumulated manufacturing experience, the engineering team evaluated alternative processes and recommended powder metallurgy (PM) as a superior, cost-saving option. PM involves compacting iron powder into a mold under high pressure, followed by sintering (heating to fuse particles without melting), to produce near-net-shape parts.     Tube made of Powder Metallurgy (Left) and CNC machining cut (Right), side by side comparison     The client, upon reviewing the cost models, expressed strong interest. PM resolved supply variability—ensure consistent 1.0 mm wall thickness and 10.0 mm dimensions—while simplifying logistics by eliminating long-tube handling and cutting. Let's summerize the benefits and outcomes below: 1.) Cost Savings Mold investment recouped within two years; overall per-unit savings of 40-50%, enabling the client to improve margins without quality trade-offs. 2.) Process Efficiency Reduced from 5-7 steps (sourcing, fixturing, cutting, tumbling, deburring) to 3 (molding, sintering, inspection), cutting lead times by 60% and labor by 80%. 3.) Quality and Reliability Burr-free parts and no dimensional drift from batches. Enhanced repeatability supports just-in-time delivery. 4.) Client Feedback The solution aligned with the client's need for "High Quality, Low Cost, and Fast delivery" production. As they noted, partnering with Apporo provided an economical, stable alternative that transformed a problematic process into a competitive advantage.   This case exemplifies how Apporo's innovative proposals turn manufacturing challenges into opportunities for efficiency and partnership. For similar consultations, contact our engineering team. Apporo's expertise in adaptive manufacturing not only met immediate needs but positioned the client for scalable growth. ...

The client, a manufacturer in the automotive assembly sector, required a batch of cylindrical stainless steel CNC machining parts with a central blind hole. These parts were integral to a sub-assembly where epoxy adhesive was used to bond them to mating components. During the initial inquiry and quoting process, the client specified two key modifications to the CNC machining: ・Increase friction on the outer diameter (OD) The client requested surface treatments such as sandblasting or slightly rougher turning to enhance the mechanical interlocking with the adhesive, thereby improving bond strength and preventing slippage during curing and operation. ・Keep smooth end faces Both ends of the cylinder must remain untreated by sandblasting, preserving a post-lathe machined finish with a surface roughness (Ra) of 0.8 μm or better. This was critical for aesthetic reasons and to ensure compatibility with downstream assembly processes, such as sealing or mating with flat surfaces. The rationale behind the OD friction enhancement was straightforward: the adhesive's effectiveness relied on surface topography to create micro-mechanical anchors, distributing stress more evenly and reducing the risk of debonding under vibration or thermal cycling.   Problem Analysis The engineering team conducted a thorough feasibility assessment, considering the part's geometry and the client's dual requirements. Key insights included: ・Challenges with Sandblasting Sandblasting is an effective method for increasing surface roughness by creating a uniform, pitted texture that promotes adhesive wetting and mechanical grip. However, applying it selectively only to the OD while protecting the end faces posed significant production hurdles. Options like masking the ends with tape or fixtures could lead to inconsistencies, contamination, or additional setup time. Alternatively, oversanding the entire part and then re-machining the ends on a lathe for refinement would increase cycle times, material waste, and costs—potentially by 20-30% per part due to the need for secondary operations. ・Limitations of Rough Turning Simply adjusting the lathe feed rate for a coarser OD finish (e.g., increasing from 0.1 mm/rev to 0.3 mm/rev) could achieve some roughness. However, this approach might not deliver the desired adhesive performance. Coarser turning often results in irregular peaks and valleys that are too large-scale for optimal glue penetration, potentially leading to weak bonding zones rather than the fine texture needed for capillary action and uniform stress distribution. Testing indicated a possible shortfall in bond strength compared to the client's benchmarks.   These considerations highlighted the need for a solution that balanced roughness enhancement with precision control, minimizing additional steps while ensuring repeatability across high-volume production.   Implementation of "Glue Grooves" To address the challenges, the engineering team recommended a custom threading-inspired technique on the OD using standard lathe tooling. This method, internally dubbed "glue grooves," involved: ・Tooling and Parameters Employing a 60-degree threading insert (commonly used for external threads) with minimal infeed (e.g., 0.05-0.1 mm depth) and a fixed pitch (e.g., 0.5-1.0 mm). The CNC lathe program was modified to traverse the OD longitudinally, creating a series of fine, helical grooves resembling miniature external threads. ・Surface Characteristics The resulting texture provided a tactile roughness detectable by fingernail scraping, with groove depths and spacing optimized for adhesive flow. This micro-texture increases the effective surface area by 15-25% (based on preliminary profilometer measurements) without compromising the part's dimensional tolerances. Crucially, the end faces remained untouched during this operation, naturally retaining the smooth Ra 0.8 μm finish from the initial facing cuts. ・Production Integration The glue grooves were incorporated into the primary lathe cycle, adding only few seconds per part—far less disruptive than sandblasting setups. No secondary masking or refinishing was required, reducing labor and scrap rates.     Glue grooves on a cylindrical stainless steel parts     Post-implementation trials, including pull-off adhesion tests per ASTM D4541 standards, demonstrated a 30-40% improvement in bond strength compared to smooth-turned samples, aligning closely with the client's performance goals. The client approved the approach during prototyping, leading to full-scale production of 5,000 units with zero defects related to surface finish.   Additional Recommendations While the glue grooves proved highly effective, the engineering team suggests exploring complementary or alternative strategies for similar applications to further refine outcomes: ・Hybrid Surface Treatments For parts with glue grooves requiring even higher friction, we recommend applying a strong degreasing process (e.g., nitric acid passivation for stainless steel, chemical conversion for aluminum alloy, acid pickling for steel). This could amplify roughness without affecting ends. ・Advanced Machining Alternatives If volume justifies investment, integrate CNC knurling tools with diamond-pattern dies for the OD. This produces a cross-hatch texture that enhances grip in multiple directions, potentially increasing bond strength by another 10-20%. Learn more about Knurling (DIN 82).     Knurling parts' OD to enhance adhesive bonding     These techniques are adaptable for various cylindrical geometries and materials, making it a versatile addition to the company's process library. By the way, the solution promoted by Apporo met all specifications, with the client reporting enhanced assembly reliability in field tests. Future orders have incorporated glue grooves as a standard option. This case study underscores the value of innovative problem-solving in precision manufacturing, transforming potential constraints into competitive advantages. For inquiries on implementing similar solutions, contact our team. ...

A client designed a low-carbon steel CNC machining part measuring 1500mm long, 19.05mm wide, and 38.1mm high. This door support guide component required five equally spaced countersunk holes to be drilled along the 19.05mm wide face, centered left to right. During first article inspection, it was discovered that the drilled holes were misaligned, compromising the part’s functionality and precision. Discussions between the QC and engineers team revealed that the root cause was insufficient fixturing during the drilling process: The component was held in place using an inadequate number of vises, which failed to secure the long, slender part properly. The lack of sufficient clamping allowed the material to shift or flex during drilling, resulting in misaligned holes that deviated from the specified positions. This misalignment could affect the part’s assembly accuracy, structural integrity, and overall performance in its intended application.     Fixing Misaligned Holes in a CNC Machining Steel Part       Implemented Solution To address the misalignment issue, the engineering team took the following corrective actions: Increased Vise Clamping: The number of vises used to secure the component was increased to four, strategically placed along the 1500mm length to provide robust and even clamping force. This ensured the part remained stable and rigid during drilling. Straightness Verification: Before drilling, a dial indicator was used to measure the straightness of the component, confirming it was within a tolerance of 0.1mm. This step ensured the part was properly aligned and free of deflection prior to machining. Redrilling Countersunk Holes: With the improved fixturing and verified straightness, the five countersunk holes were redrilled, achieving the required equal spacing and centered positioning on the 19.05mm face. These adjustments resulted in accurately positioned holes that met the client’s specifications and passed QC inspection.   Increased Vise Clamping and Straightness Verification     Professional Machining Recommendations To prevent similar issues in future projects and optimize the machining process, the following recommendations are proposed: Optimize Fixturing Design: For long, slender components like this one, use a minimum number of vises or custom fixtures to distribute clamping force evenly along the length. Ensure vises are positioned to minimize deflection, particularly near the drilling locations, and use soft jaws or padded clamps to avoid surface damage to the low-carbon steel. Pre-Machining Inspection: Always verify the straightness and flatness of the workpiece using precision tools like a dial indicator before machining. A tolerance of 0.1mm or better is recommended for high-precision applications. Tooling and Process Optimization: Use high-precision drilling tools with appropriate cutting parameters (e.g., feed rate and spindle speed) suited for low-carbon steel to minimize vibration and ensure clean cuts. Consider peck drilling for deep countersunk holes to reduce heat buildup and improve chip evacuation, further enhancing accuracy. Quality Control Enhancements: Implement in-process inspections using coordinate measuring machines (CMM) or laser scanning to verify hole positions during machining, catching potential misalignments early. Document fixturing setups and straightness measurements for traceability and to standardize processes for similar components.   Conclusion The misalignment of countersunk holes in the 1500mm x 19.05mm x 38.1mm low-carbon steel CNC machining part was caused by insufficient vise clamping, allowing the part to shift during drilling. By increasing the number of vises, verifying straightness within 0.1mm, and redrilling the holes, the engineering team resolved the issue and delivered a part that met specifications. The proposed recommendations, including optimized fixturing, pre-machining inspections, and enhanced quality control, will help ensure precision and reliability in similar machining projects, preventing future drilling disasters and ensuring client satisfaction. ...

In a recent project, a client specified a design for a CNC machining component featuring an M22x2.0 external thread with a thread length of only 3.0mm, equals approximately 1.5 thread turns. The thread base connects to a larger outer diameter, and initially lacked a thread relief (runout) groove. This component is intended to be screwing into an internal threaded mating part.      Threaded component assembly by using improper thread may result in interference and out of function     Problem Statement The design presented two primary issues that could compromise the functionality and reliability of the assembly: Insufficient Thread Length: When considering incomplete threads (chamfered at the start or imperfect threads at the end), the effective thread engagement may be reduced to ONLY one turn or less. This limited engagement could significantly weaken the connection, reducing the assembly's strength and reliability during operation. Lack of Thread Relief Groove: Without a relief groove, the external thread may not fully engage with the internal threaded component, preventing a secure and complete connection. During assembly, the transition from the threaded section to the larger outer diameter can cause interference with the internal thread, preventing full engagement. This could result in improper seating, increased stress concentrations, or even damage to the threads during assembly. Inadequate Thread Turns: Industry standards from ISO or ASME typically recommend a minimum thread engagement of at least 1 to 1.5 times the thread diameter for sufficient strength, which would be approximately 22–33mm for an M22 thread. With only 3.0mm of thread length, the effective engagement is inadequate, particularly when factoring in incomplete threads.   Proposed Improvements To address these issues and enhance the component’s performance, the following solutions are proposed: Increase Thread Length: Increase the thread length to at least 6.0mm (approximately 3 turns for M22x2.0) to ensure sufficient engagement for a strong, reliable connection. Add a Relief Groove: Incorporate a relief groove at the thread base where it meets the larger outer diameter. This allows the external thread to fully engage with the internal thread without interference. Enlarge Chamfer on Internal Thread: A larger chamfer at the entrance of the internal threaded hole accommodates incomplete threads or runout on the external thread, ensuring smoother assembly and reducing the risk of thread damage. Redesign Thread Specification to M21x1.5: Given sufficient space in the inner and outer diameters of both components, modify the thread specification to M21x1.5. This finer thread pitch allows more thread turns within the same length (e.g., 6.0mm would yield 4 turns), significantly improving engagement and connection strength.   ...

Building on the positive reception of our previous analysis regarding manufacturing processes (see Apporo CNC Analysis: Fine Blanking Press Can Save 90% of Manufacturing Cost), Apporo Industries is now exploring the shift from laser cutting or NCT (Numerical Control Turret Punching) production methods to utilizing stamping dies for manufacturing. The decision to switch from laser cutting or NCT to stamping die production involves significant changes in the manufacturing process. Laser cutting and NCT are known for their flexibility and precision in cutting various shapes and materials, but stamping dies offer a different set of benefits and challenges when it comes to mass production.    This transition is aimed at enhancing production efficiency, quality, and cost-effectiveness. Our analysis of Advantages and Disadvantages of Stamping Die Production shows below: Consistency: With stamping dies, once the tool is correctly designed and made, the consistency of parts is very high. This reduces variability in part quality, which might occur with laser cutting due to material thickness variations or with NCT due to tool wear. Setup Time: While laser cutting and NCT offer quick setup changes for different designs, stamping dies require more time for setup and changeover. This can be a disadvantage for low-volume or highly varied production but is less of an issue for high-volume runs. Cost Efficiency for High Volumes: For large production runs, the cost per stamping part decreases as the volume increases, unlike laser cutting where costs remain relatively constant. Material Utilization: Stamping dies often allow for better material utilization as they can be designed to minimize waste. Initial Costs: The upfront cost for designing, manufacturing, and setting up stamping dies is significantly higher than for laser cutting or NCT. This makes it less economical for small batch sizes or for products with frequent design changes. Flexibility: Once a tooling is made, changing the design or producing different parts requires either modifying the existing die or creating a new one, which is usually time-consuming and costly. Laser cutting and NCT provide more flexibility for design iterations. Tool Wear: While less of an issue than with NCT, stamping dies still experience wear over time, especially with harder materials, which can affect part quality and require maintenance or replacement.   For products with stable designs and large production quantities, press dies offer a compelling solution. However, for smaller runs or pre-sample products requiring frequent design changes, sticking with laser cutting or NCT might be more practical. These two types of sheet metal processing methods can actually complement each other, helping with the efficient design and production of products. Here is a practical example illustrating how Apporo Industries transitioned from laser cutting for design verification to stamping die production for mass production： Design Verification with Laser Cutting As shown in the first image below, the stainless steel flat plate was initially designed to be laser cut for prototyping to verify that the dimensions met the assembly requirements. The design included two specific outer diameter features, indicated by red arrows, which were tailored for laser cutting to ensure that after cutting, the part would be easily detached from the original sheet material. These features were designed so that the cut points (break-off points) would not exceed the maximum outer diameter, thereby not affecting the assembly process. This step allowed for quick adjustments and validation of the design before moving to mass production by the stamping die processing.   If these design considerations, indicated by the red arrows, were not included, the cutting nibs would remain on the outer diameter, as discussed in a previous case study (see Apporo CNC Analysis: Post-Cutting Nib Removal on Precision Flat Washer Parts). Such cutting nibs could interfere with subsequent assembly, causing interference issues. Therefore, incorporating these design features was a brilliant move.   Design verification with laser cutting     Transition to Stamping Die Production After validating the dimensions through laser cutting, the design was finalized and transitioned to production via stamping dies, as seen in the second image. The final product, manufactured with a stamping die, features a complete circular outer diameter without any break-off point designs, enhancing the finish and structural integrity of the part.    Transition to stamping die production     The above change from laser cutting to press die production not only improved the quality of the finished product by eliminating any design compromises for cutting but also facilitated high-volume manufacturing with greater efficiency. Apporo Industries will continue to evaluate these factors to optimize our production processes, ensuring we deliver the highest quality products efficiently.   ...

The Quality Control (QC) team at Apporo Industries identified an issue with CNC milling machined parts returned from a galvanizing supplier. Specifically, the edges of the threaded blind holes exhibited yellow rust spots. These blind holes, which do not pass through the entire part, were likely not fully dried after the galvanizing process, leading to residual chemicals and solutions inside the holes. It reminds us that there was a similar to a previous analysis conducted by Apporo Industries on aluminum alloy threaded holes (refer to Apporo CNC Analysis).   Rust Formation in Threaded Blind Holes Post-Galvanization     After analysis, the causes that may lead to rusting inside the hole are as follows： 1.) Chemical Reaction: The rust formation is likely due to the presence of residual acidic solutions from the galvanizing process that were not completely dried or neutralized. When these solutions react with the metal, especially in confined spaces like blind holes, rust can form. 2.) Environmental Factors: The environment in which the parts were stored or transported after galvanization could have contributed to the rusting if there was moisture present. 3.) Material Properties: The material of the part might have an inherent susceptibility to rust formation under certain conditions, particularly if not properly protected by the galvanizing layer.   Anti-rust Improvement Measures: Rust can be caused by many different factors, and once it starts, it can get worse if not treated properly and promptly. Therefore, avoiding rust is very important. Here are some suggested methods to prevent rust: 1.) Enhanced Drying Process: Implementing a more strict drying process post-galvanization, especially focusing on ensuring that all internal cavities and blind holes are thoroughly dried. This could involve using forced air drying, vacuum drying, or heat treatment to evaporate any trapped moisture or chemicals. 2.) Chemical Neutralization: After galvanizing, a neutralization step could be added to the process to counteract any residual acidic effects, reducing the likelihood of rust formation. 3.) Inspection Protocols: Strengthening inspection protocols to include specific checks for moisture or chemical residue in blind holes before parts leave the galvanizing facility. 4.) Material Coating: Considering the application of a protective sealant or additional coating inside the blind holes to prevent direct contact with moisture or air, which could initiate rusting. 5.) Storage and Transportation: Ensuring that parts are stored in a controlled environment with low humidity and are transported in packaging that minimizes exposure to moisture.   By implementing these measures, Apporo Industries aims to prevent future occurrences of rust in threaded blind holes post-galvanization. The case underscores the importance of thorough post-treatment processes in galvanizing, particularly for CNC milling machined parts with complex geometries like blind holes, to ensure the longevity and quality of the finished product.   ...

We encountered an issue with precision flat washer parts after cutting operations using laser cutting, where our quality team reported that both the inner and outer diameters had residual sharp nibs.   Cutting Nib on Precision Flat Washer Parts     These nibs, common in processes like laser cutting, water jet, or flame cutting, can interfere with assembly if the cut surface is intended for mating with other components. Below are possible causes of nib formation: Material Properties: Certain softer materials, like aluminum due to their ductility or hardness, might deform more during cutting, leading to nibs. Cutting Parameters: Incorrect settings such as speed, power, or focus in laser cutting can lead to uneven cutting and nib formation. Similarly, in water jet cutting, water pressure and abrasive flow rate can influence nib creation. Tool Wear: In processes like flame cutting, worn nozzles or cutting tips can cause irregular cuts and subsequent nibs. Design Considerations: Sometimes, the design of the part itself, like sharp internal corners or thin walls, can exacerbate nib formation. Upon receiving the report, the engineering department immediately ground the parts to remove the sharp nibs, ensuring the dimensions remained within the specified tolerances for proper assembly.   Post-Cutting Nib Removal on Precision Flat Washer Parts by using grinding     After resolving this issue, the engineering department also developed the following preventive measures for the future: Optimizing Cutting Parameters: Regular calibration and adjustment of cutting parameters to match material properties can reduce nib formation. For laser cutting, this might involve adjusting the laser power, speed, and focus. Tool Maintenance: Regular inspection and maintenance of cutting tools to ensure they are in good condition, reducing the likelihood of nibs due to tool wear. Design for Manufacturability: Modifying part designs to minimize sharp edges or stress points where nibs are likely to form. This might include adding slight radii to corners or adjusting wall thickness. Post-Processing Automation: Implementing automated deburring processes or robotic finishing can ensure consistency and reduce human error in nib removal. Quality Control Checks: Implementing strict inspection protocols post-cutting to catch nib issues early, allowing for immediate correction before parts move to assembly.   ...

A customer raised a significant concern regarding external threads on a CNC machined part specified as 3 7/8-16 UN-2A, pinpointing the presence of burrs along the threads, as evidenced by the attached images. Although the part passed the ring gauge test, which focuses on thread dimensions and form, it failed to address the critical surface finish issue of burrs.  Burrs are present along threads    Root Cause Analysis Initially, the engineering team tried to machine the chamfer as per the drawing specified C0.889 x 45 degrees, but this left only about 2 effective thread turns due to the part's thickness being only 5.207 mm, raising concerns about strength. The calculation for this is as follows: Effective Thread Turns = (5.207−0.889×2) / (25.4/16) = 2.16 To increase the number of effective threads, the engineering team reduced the chamfer size to around C0.5 x 45 degrees, which unfortunately made the thread flanks at both ends too thin, leading to easy burr formation or deformation.   Solution Implemented After a discussion with the customer, our decision was made to machine the chamfer size to C0.889 x 45 degrees on both thread ends, following the drawing specifications, to avoid deformation and burring due to the thin thread flanks. This adjustment might reduce the effective thread to about 2 turns or even less, but given that the thread does not need to bear heavy loads, the customer agreed to this critical compromise, getting rid of burrs over the thread. Additionally, they suggested a full inspection of the external thread quality, with the option to use a scraper or file to remove any burrs if necessary. This case study also taught the team that thorough and proper communication beforehand is far better than reviewing the causes and implementing improvements after an issue has occurred.   ...

An issue of rust formation on a motor plate component, which was deemed non-compliant by a customer after delivery. The motor plate, made of carbon steel, was processed through CNC milling, then oiled, properly sealed for packaging before being shipped via sea freight. Upon inspection by the customer, rust spots were observed, leading to the rejection and return of the parts. Rust Formation on Motor Plate       Analysis of Rust Formation Causes Our analysis suggested that the use of water-based cutting fluid during the CNC milling process might not have been fully removed post-machining. Despite applying rust-preventive oil, residual moisture or cutting fluid could have led to the rusting of the component during transit or storage. 1.) Residual Moisture: Even after machining, if water-based cutting fluids are not completely removed, they can leave moisture on the surface which can initiate rust. Inadequate Rust Prevention: The anti-rust oil might not have been applied uniformly or thick enough to provide a barrier against moisture, especially in a humid or salty environment like sea freight. 2.) Environmental Factors: During sea transportation, the components could have been exposed to high humidity, salt air, or temperature fluctuations, all of which accelerate rust formation. 3.) Packaging Issues: If the packaging was not sufficiently sealed or if there was any breach during transit, external moisture could have penetrated, leading to rust.   Rust Formation on Motor Plate   Improvement Measures The possible causes may be numerous, and our suggested preventive measures that we can take are as follows: 1.) Enhanced Cleaning: Implement an advanced cleaning process after milling to ensure all cutting fluids are removed. This could involve ultrasonic cleaning or high-pressure air drying. 2.) Improved Rust Prevention Application: Use a more effective rust inhibitor or increase the thickness of the oil layer applied.Consider dipping or spraying the parts in a rust-proofing solution that forms a more robust protective layer. 3.) Controlled Environment Packaging: Use vacuum-sealed or desiccant-based packaging to minimize moisture exposure during transit.Employ corrosion-inhibiting packaging materials or VCI (Volatile Corrosion Inhibitors) to provide additional protection.   The rust formation on the motor plate was likely due to a combination of residual moisture from CNC machining, inadequate rust prevention measures, and environmental exposure during shipping. By implementing the suggested improvements in cleaning, rust prevention, and packaging, future occurrences can be significantly reduced, and ensure product quality.   ...

In the precision manufacturing industry, ensuring the quality of materials through accurate testing is crucial. This case study examines a situation where a customer reported that the surface hardness of a CNC machined tubular component did not meet the required standards due to incorrect testing methods. The study highlights the importance of proper measurement techniques and how they can significantly affect the results.   Background The client received a batch of tubular components and conducted a hardness test, reporting that the surface hardness was below the specified standard of HRC 48-52, measuring only around HRC 43. This discrepancy led to concerns about the quality of the component being manufactured. However, upon our engineering team’s investigation, it was found that the customer's method of testing was flawed.   Incorrect Measurement Method The customer's approach, as depicted in the photo below, involved laying the tubular part horizontally and measuring hardness from the outer diameter towards the center using a hardness tester probe. This method resulted in: Hardness measurement by client   1.) Probe Alignment Issue: When the tubular part is placed horizontally, it's challenging to ensure that the hardness tester probe is perfectly perpendicular to the surface at the maximum outer diameter of the part. Any slight eccentricity in the placement of the probe can lead to inaccurate readings. This misalignment can cause the probe to measure at an angle, which affects the depth of penetration and, consequently, the hardness value. 2.) Potential Deformation: The round tube might likely deform under the force applied by the hardness tester probe, especially when the probe is applied from the side, which could deviate the measurements. 3.) Low Hardness Reading: The recorded hardness was approximately HRC 43, significantly lower than the expected standard.   Correct Measurement Method The proper method for measuring the hardness of tubular components, as shown in the photo below, involves the following steps: Correct hardness measurement by Apporo   1.) Preparation: To ensure that the measurement is taken on a flat surface. 2.) Setup: The tubular part is placed on the hardness tester with the cut end facing upwards. It is crucial that the workpiece is supported stably from below to prevent any movement or deformation during testing. 3.) Measurement: Using a Rockwell Hardness Tester, as seen in the image, the probe is applied directly to the exposed end face of the tube wall. This approach minimizes the risk of deformation and provides a true representation of the component's hardness. 4.) Result: The correct measurement, as shown in the image, yielded a hardness of HRC 50.3, which meets the required standard.   This case study demonstrates the critical role of proper measurement techniques in quality assurance. The customer's initial complaint was resolved by demonstrating the improved method of hardness testing for tubular components, which resulted in a hardness reading that met the specified standards. It highlights the need for education on testing methodologies to prevent misinterpretation of material properties and underscores the importance of accurate, standardized testing procedures in maintaining product quality and trust between manufacturers and their clients. We highly encourage customers to verify testing methods with Apporo before concluding that a CNC machined part is non-compliant, to avoid unnecessary disputes. ...

Tumbling, also known as vibratory finishing, is frequently used in the post-processing of CNC machined parts to remove sharp edges and burrs. However, the narrow groove edges might have been deformed due to the impact from tumbling, causing the groove width to shrink and making it impossible to assemble the C-clip.   The image above shows the deformation at the edge highlighted by the red arrow.   To address this issue, the following improvement plan has been proposed: ・Increase the Chamfer Size Design a larger chamfer on the edges to accommodate for any potential deformation during the finishing process, ensuring the slot remains adequately sized for the C-clip. ・Cease Tumbling Originally, tumbling was used to deburr and break the sharp edges. If vibratory finishing is ceased to prevent the unwanted deformation, the part must be machined with a chamfer on the lathe to deburr. ・Increase Tolerance Adjust the groove dimensions to include a wider tolerance on the upper limit, or suggest to the customer to slightly increase the groove width to ensure assembly with the C-clip.   By implementing the above changes, we aim to prevent similar issues in the future, ensuring parts are machined to specification and can be assembled as intended.   ...