Machine Reamer

Machine reamers are essential cutting tools used to enlarge or refine existing holes to precise dimensions and smooth finishes. They provide tighter tolerances and superior surface quality compared to drilling. This article explores the various types of machine reamers, their applications, selection criteria, and best practices for achieving optimal results.What is a Machine Reamer?A machine reamer is a rotary cutting tool designed to enlarge or finish a pre-drilled hole to a precise size and shape. Unlike drills, reamers don't create the hole but improve its accuracy and surface finish. They are commonly used in manufacturing, metalworking, and machining operations where tight tolerances are crucial.Types of Machine ReamersMachine reamers come in various designs, each suited for specific applications. Here's an overview of common types: Straight Reamers: General-purpose reamers for producing accurate holes in a variety of materials. Tapered Reamers: Used to create tapered holes, often for fitting tapered pins or fasteners. Hand Reamers: Designed for manual use, typically with a square end for wrenching. While not strictly machine reamers, understanding them provides context. Adjustable Reamers: Offer the flexibility to adjust the cutting diameter within a small range. Shell Reamers: Consist of a reamer body (shell) mounted on an arbor. Economical for larger diameter reamers. Carbide Reamers: Feature carbide cutting edges for enhanced wear resistance and suitability for hard materials. Expansion Reamers: Allow for a slight expansion of the cutting diameter to compensate for wear or to achieve a specific hole size.Applications of Machine ReamersMachine reamers are employed in a wide range of applications across various industries: Automotive: Finishing valve guides, aligning piston pin bores. Aerospace: Creating precision holes for fasteners in aircraft structures. Manufacturing: Improving hole accuracy and surface finish in machined parts. Tool and Die Making: Producing accurate holes in dies and molds. Medical Devices: Creating precise holes in surgical instruments and implants.Selecting the Right Machine ReamerChoosing the appropriate machine reamer is crucial for achieving the desired results. Consider the following factors:Material to be ReamedThe material's hardness, machinability, and abrasiveness will influence the choice of reamer material (e.g., high-speed steel (HSS), carbide) and coating.Hole Size and ToleranceSelect a reamer with the correct diameter and ensure it can achieve the required tolerance. Adjustable reamers can be useful for fine-tuning hole sizes. The high-quality machine reamers offered by Wayleading Tools are designed for precision.Hole DepthFor deep holes, choose a reamer with sufficient flute length to allow for chip evacuation. Consider using a coolant-through reamer for deep hole applications.Machine TypeEnsure the reamer shank is compatible with the machine spindle or chuck. Consider the machine's speed and feed capabilities.Surface Finish RequirementsThe number of flutes and the reamer's cutting geometry will affect the surface finish. For very fine finishes, consider using a burnishing reamer.Best Practices for Using Machine ReamersFollowing these best practices will help maximize the performance and lifespan of your machine reamers:Proper Hole PreparationEnsure the pre-drilled hole is clean, free of burrs, and slightly undersized for the reamer. The pre-drilled hole should be within 0.004' to 0.015' of the final hole size, depending on the material and reamer diameter. Too large a hole will result in poor accuracy and finish; too small a hole will overload the reamer.Correct Speed and FeedUse the recommended cutting speed and feed rate for the reamer and material. Generally, reaming speeds are lower than drilling speeds. Consult a machining handbook or the reamer manufacturer's recommendations.Here's a general guideline for speeds and feeds. These values should be adjusted based on material and specific reamer type. Material Surface Speed (SFM) Feed Rate (IPR) Mild Steel .001-0.004 Aluminum .002-0.006 Stainless Steel .0005-0.003 Source: Machinery's HandbookAdequate Coolant and LubricationUse appropriate coolant to dissipate heat, lubricate the cutting edges, and flush away chips. Coolant is especially important for deep hole reaming and for materials that generate a lot of heat. A good coolant can increase reamer life significantly.Proper Tool HoldingUse a rigid tool holder that provides accurate alignment and minimizes vibration. Collet chucks are often preferred for reaming due to their superior accuracy and gripping power.Sharp ReamersEnsure the reamer is sharp. Dull reamers will produce poor surface finishes, oversized holes, and can cause premature tool wear. Resharpen reamers regularly to maintain optimal performance.Chip EvacuationEnsure proper chip evacuation to prevent chip packing and tool damage. Use coolant-through reamers or peck reaming techniques for deep holes.Avoiding Interrupted CutsWhenever possible, avoid interrupted cuts (e.g., holes with keyways or slots). Interrupted cuts can cause chipping and premature tool failure. If interrupted cuts are unavoidable, reduce the cutting speed and feed rate.Machine Reamer Materials and CoatingsThe material and coating of a machine reamer significantly impact its performance and lifespan:High-Speed Steel (HSS)HSS reamers are a versatile and cost-effective option for general-purpose applications. They offer good toughness and wear resistance.CarbideCarbide reamers provide superior hardness and wear resistance, making them suitable for machining hard materials and abrasive materials. They can withstand higher cutting speeds than HSS reamers.CoatingsCoatings can enhance the performance of reamers by reducing friction, increasing wear resistance, and improving chip flow. Common coatings include: Titanium Nitride (TiN): A general-purpose coating that improves wear resistance and tool life. Titanium Carbonitride (TiCN): Offers higher hardness and wear resistance than TiN. Aluminum Titanium Nitride (AlTiN): Provides excellent heat resistance and is suitable for high-speed machining.Troubleshooting Common Reaming ProblemsEven with proper techniques, problems can sometimes arise during reaming. Here are some common issues and their potential solutions:Oversized Holes Cause: Dull reamer, excessive cutting speed, insufficient support, excessive play in the machine spindle. Solution: Sharpen or replace the reamer, reduce cutting speed, ensure proper support, check and repair machine spindle.Poor Surface Finish Cause: Dull reamer, improper coolant, excessive feed rate, vibration. Solution: Sharpen or replace the reamer, use appropriate coolant, reduce feed rate, improve tool holding and machine stability.Tapered Holes Cause: Misalignment of the reamer and workpiece, worn machine spindle. Solution: Ensure proper alignment, check and repair machine spindle.Chatter Cause: Excessive cutting speed, insufficient rigidity, vibration. Solution: Reduce cutting speed, improve tool holding and machine stability, use a reamer with more flutes.ConclusionMachine reamers are critical tools for achieving precise hole dimensions and smooth surface finishes. By understanding the different types of reamers, their applications, and best practices for their use, you can optimize your machining operations and produce high-quality parts. Remember to choose the right reamer for the job, maintain proper cutting conditions, and troubleshoot any issues that may arise. Wayleading Tools offers a comprehensive range of machine reamers to meet your specific needs; visit www.wayleading.com to explore our selection.