Hard metal cutting is where most conventional tools fail fast. Titanium alloys, tungsten, and molybdenum share a reputation that anyone who’s machined them knows well: they destroy tooling. Ti-6Al-4V eats carbide inserts because the heat has nowhere to go — its thermal conductivity is roughly 7 W/m·K, about one-sixth of steel. Pure tungsten is harder than most cutting tools (HV 350–450 for wrought tungsten) and sits at the edge of room-temperature brittleness, meaning it can crack without warning during a cut. Molybdenum is slightly more forgiving in ductility, but it oxidizes aggressively above 500°C, so any cutting process that generates serious heat leaves a discolored, oxide-contaminated surface that needs to be ground away.
These are all materials where the workpiece costs far more than the cutting operation itself. A 50 mm × 50 mm × 200 mm billet of Ti-6Al-4V runs $300–600; a similar-sized tungsten block can exceed $1,000. Wasting material to wide kerf or scrapping parts due to thermal damage is expensive. That’s exactly where 다이아몬드 와이어 커팅 earns its place: cold process, narrow kerf, no heat-affected zone, and surface quality that often eliminates secondary grinding.
This article walks through the specific challenges of hard metal cutting for each of these three materials, where conventional methods fall short, and the process parameters we use for diamond wire sawing.
What Makes Hard Metal Cutting So Difficult?
Each of these three metals fails differently under conventional machining, but they share a common thread: the cutting process itself tends to damage the material or the tool, or both.
Titanium Alloys (Ti-6Al-4V, Ti Grade 2, Ti-6Al-2Sn-4Zr-2Mo)
Ti-6Al-4V (ASTM B265 Grade 5) accounts for roughly 70% of all titanium alloy usage globally. It’s about 40% lighter than steel at comparable strength — which makes it the go-to material for aerospace structural parts, medical implants, and marine hardware.
The machining problem comes down to three properties working against you simultaneously:
Thermal conductivity of 7 W/m·K. For comparison, mild steel is around 50 W/m·K and aluminum is 200+ W/m·K. When you cut titanium, the heat generated at the cutting interface has almost no path into the workpiece bulk. It stays concentrated at the tool tip and the cut surface. This accelerates tool wear and can create localized hot spots above 600°C, which is well into the temperature range where titanium becomes chemically reactive with tool materials — bonding to carbide surfaces and causing adhesive wear.
High elasticity (low modulus). Titanium’s elastic modulus is about 114 GPa, roughly half that of steel. During cutting, the workpiece deflects away from the tool and then springs back. This causes rubbing rather than clean material removal, which generates additional heat and produces poor surface finish. It’s also why thin-walled titanium parts are notoriously difficult to machine — they flex under cutting forces and chatter.
Work hardening. Similar to austenitic stainless steels, titanium alloys harden at the surface during cutting. If a tool dwells or rubs without removing material, the surface work-hardens and subsequent passes become progressively more difficult. This creates a vicious cycle: the harder surface generates more heat, which dulls the tool faster, which causes more rubbing.
Tungsten (Pure W, W-Ni-Fe, W-Cu)
Pure tungsten has a Vickers hardness of 350–450 HV (wrought) and a melting point of 3,422°C — the highest of any metal. It’s used in radiation shielding, high-temperature furnace components, counterweights, and electrical contacts. The ASTM B760 specification covers tungsten plate and sheet for these applications.
The defining machining challenge is the ductile-to-brittle transition temperature (DBTT). At room temperature, pure tungsten is borderline brittle. The DBTT for commercially pure tungsten typically sits between 200°C and 400°C depending on processing history, grain structure, and impurity content. Below the DBTT, tungsten fractures in a transgranular cleavage mode — cracks propagate through grains with minimal plastic deformation. This means any cutting method that applies high mechanical stress at room temperature risks cracking the workpiece.
Conventional machining of tungsten is largely limited to diamond grinding and wire EDM. CNC milling with carbide tools is possible on some tungsten alloys (W-Ni-Fe heavy alloys are more ductile), but pure tungsten and W-Cu composites will chip and crack under the interrupted cutting forces of milling.
One more complication: tungsten is dense — 19.3 g/cm³, nearly 2.5 times heavier than steel. This means even small workpieces are heavy, and fixture design needs to account for the mass. Gravity-loaded test cuts can be a real headache if the part shifts during cutting.
Molybdenum (Pure Mo, TZM)
Molybdenum sits between tungsten and titanium in machining difficulty. Its hardness is moderate (HV 200–300 for wrought Mo), and it has somewhat better room-temperature ductility than tungsten. TZM alloy (Mo-0.5Ti-0.1Zr) is the most commonly machined grade, used in high-temperature structural parts, heat sinks, and semiconductor processing equipment.
The problems:
Oxidation above 500°C. Molybdenum forms volatile MoO₃ at elevated temperatures. The oxide evaporates rather than forming a protective layer, so the metal literally erodes when hot. Any cutting process that heats the surface above 500°C leaves an oxidized, pitted surface. This rules out laser cutting for precision work and makes thermal management critical during abrasive cutting.
Low fracture toughness at room temperature. Like tungsten, molybdenum has a DBTT — typically around 0°C to 100°C for wrought material, lower than tungsten but still close enough to room temperature that brittle fracture is a concern during aggressive cutting.
Smearing. When machined with conventional tools at insufficient cutting speeds, molybdenum tends to smear rather than form clean chips. This produces a built-up edge on the tool and a torn, rough surface on the workpiece.
Why Diamond Wire Saw Works for Hard Metal Cutting
The common thread across titanium, tungsten, and molybdenum is that conventional cutting generates too much heat, too much mechanical stress, or both. A 다이아몬드 와이어 톱 addresses this by operating on a fundamentally different removal mechanism: micro-grinding with a flexible tool at high linear speed and low unit cutting force.
Thermal Control Without Compromise
그만큼 다이아몬드 와이어 루프 moves at 40–70 m/s. Each diamond particle contacts the workpiece for microseconds, removes a microscopic chip, and moves on. The heat generated per particle is minuscule, and it’s spread across the entire wire circumference rather than concentrated at a single cutting edge.
Combined with continuous coolant delivery (water-based or light mineral oil), this keeps the cutting zone well below 100°C. We’ve measured surface temperatures of 50–70°C during titanium cutting under standard parameters. For molybdenum, this means no MoO₃ formation. For tungsten, it means no thermal stress that would push a borderline-brittle material over the edge into cracking.
This isn’t just about protecting the workpiece. For titanium in particular, the low cutting temperature also means no chemical bonding between the workpiece and the tool — the mechanism that destroys carbide inserts in conventional titanium machining simply doesn’t apply here because the diamond particles don’t reach the temperatures where titanium becomes chemically aggressive.
Low Mechanical Stress Prevents Cracking
The wire tension is set between 180–230 N for metals, and the cutting force is distributed along the contact arc between the wire and the workpiece. The peak mechanical stress at any point on the workpiece is far lower than with a rigid blade or a milling cutter. For tungsten and molybdenum, this means the material stays well within its elastic range — no concentrated stress riser that would initiate a cleavage fracture.
We’ve cut pure tungsten blocks at room temperature (22°C) without any cracking using a 0.5 mm wire at 200 N tension and 0.2 mm/min feed rate. The same blocks cracked during a band saw attempt — the teeth created localized stress concentrations that exceeded the brittle fracture threshold.
Narrow Kerf Saves Expensive Material
A 0.35–0.5 mm wire produces a kerf of approximately 0.4–0.55 mm. Compare that to a typical abrasive cutoff wheel at 1.5–3 mm kerf or even a band saw at 1–2 mm. When you’re cutting $20+/cm³ tungsten, every millimeter of kerf that becomes swarf is money lost.
On a practical example: slicing a 40 mm × 40 mm tungsten block into twenty 2 mm wafers. With a 0.5 mm kerf (diamond wire), you lose about 10 mm of block length to kerf — roughly one extra wafer’s worth of material. With a 2 mm kerf (abrasive wheel), you lose 40 mm — ten wafers’ worth. On tungsten, that’s hundreds of dollars in recovered material.
Recommended Hard Metal Cutting Parameters
The following parameters are based on our production experience on the SG20 그리고 SGI20 platforms. These are starting points — always run a test cut on your specific material before committing to production settings.
| 매개변수 | Ti-6Al-4V | Pure Tungsten | Molybdenum / TZM |
|---|---|---|---|
| 와이어 직경 | 0.35-0.5mm | 0.5mm | 0.35-0.5mm |
| 와이어 장력 | 180–220 N | 200–230 N | 180–220 N |
| 와이어 속도 | 50–70 m/s | 40-60 m/s | 50–70 m/s |
| 피드 속도 | 0.3–1.0 mm/min | 0.2–0.5 mm/min | 0.5–1.5 mm/min |
| 냉각수 | Water-based with inhibitor | Water-based or light mineral oil | Light mineral oil (preferred) |
| 일반적인 Ra | 0.3–0.6 μm | 0.4–0.8 μm | 0.3–0.5 μm |
| Dimensional tolerance | ±0.03 mm | ±0.03 mm | ±0.03 mm |
Some notes from our cutting experience:
Titanium: The biggest mistake is running the feed rate too fast. Titanium’s elasticity means the wire bow increases more per unit of feed force than with stiffer materials. If you push the feed above 1 mm/min on a 30+ mm cross-section, the wire deflects and the cut surface develops a taper. We typically start at 0.5 mm/min and increase in 0.1 mm/min steps while monitoring the wire bow with the machine’s built-in displacement sensor.
Tungsten: Slow and steady. The feed rate needs to stay low — 0.2–0.5 mm/min — not because of hardness (the diamond handles it), but because of the brittleness risk. Higher feed rates increase the instantaneous cutting force, and tungsten at room temperature doesn’t tolerate stress spikes. Use the thicker 0.5 mm wire for mechanical stability. If possible, warm the workpiece slightly (to 40–50°C) using heated coolant — this moves the material further from its DBTT and reduces fracture risk. Some labs wrap the fixture in a heating pad for the same reason.
Molybdenum: More forgiving than tungsten. The feed rate can go higher (up to 1.5 mm/min on cross-sections under 30 mm), and surface quality is consistently good (Ra 0.3–0.5 μm without much effort). The key concern is oxidation prevention — use oil-based coolant rather than water-based for best results on molybdenum. Even with water-based coolant, the cutting temperature is too low for significant MoO₃ formation, but oil provides an additional barrier against surface discoloration. After cutting, we recommend wiping the cut surface with isopropanol and storing in a desiccator if the parts won’t be used immediately.
Where Hard Metal Cutting with Wire Saw Fits Best
Metallographic Sample Preparation
This is the most common use case we see. Research labs and quality departments need cross-sections of titanium aerospace components, tungsten sputtering targets, or molybdenum heat sinks for microstructural analysis. The cut surface needs to be damage-free — no thermal artifacts, no mechanical deformation layer, no smearing — because the whole point is to examine the true microstructure.
Diamond wire sawing produces a surface with a sub-surface damage layer typically under 5 μm deep, compared to 50–200 μm for abrasive cutoff wheels. This dramatically reduces the amount of subsequent lapping and polishing needed before the sample is ready for SEM or EBSD examination.
Aerospace Component Sectioning
Titanium parts from jet engine cold-section components often need to be sectioned for failure analysis or remaining-life assessment. The cutting method can’t alter the microstructure or introduce residual stress that would confuse the analysis. Diamond wire sawing preserves the original material state right up to the cut surface.
Sputtering Target Manufacturing
Tungsten and molybdenum sputtering targets for semiconductor manufacturing need precise dimensional control and contamination-free surfaces. The targets are typically cut from larger billets into specific diameters and thicknesses. Wire EDM can do this, but it leaves a recast layer and introduces copper or brass contamination from the EDM wire electrode. Diamond wire cutting avoids both issues — no recast layer, no metallic contamination. The wire is a stainless steel core with electroplated diamond, and the only residue is easily cleaned diamond abrasive particles and coolant.
Medical Implant R&D
Ti-6Al-4V is the primary alloy for orthopedic implants (hip stems, spinal cages, dental abutments). During development, prototypes and test coupons are frequently sectioned for mechanical testing (fatigue specimens, tensile coupons) and biocompatibility evaluation. The cutting method needs to preserve the material’s fatigue properties at the cut surface, which rules out any process that introduces tensile residual stress or a heat-affected zone.
Comparing Hard Metal Cutting Methods
| 방법 | HAZ | Contamination Risk | Ra (typical) | 절단 손실 | 최상의 대상 |
|---|---|---|---|---|---|
| 다이아몬드 와이어 톱 | 없음 | 없음 | 0.3–0.8 μm | 0.4–0.55 mm | Precision samples, thin sections, high-value materials |
| 와이어 EDM | Recast layer 5–15 μm | Cu/Zn from electrode wire | 0.8–1.5 μm | 0.25–0.35 mm | Complex profiles, very tight tolerances |
| Abrasive cutoff wheel | 50–200 μm | Abrasive contamination | 1.5–3.0 μm | 1.5~3.0mm | Rough sectioning, speed priority |
| Diamond grinding wheel | 10–30 μm | 최소 | 0.2–0.5 μm | 1.0–2.0 mm | Surface finishing, not primary cutting |
| 레이저 커팅 | 100–500 μm | Oxide layer | 2.0–5.0 μm | ~0.1 mm | Sheet cutting, 2D profiles |
| 워터젯 | 없음 | Garnet embedding possible | 3.0–6.0 μm | 0.8–1.5 mm | Thick plate, no size limit |
Wire EDM deserves a specific mention because it’s the most common precision alternative for these metals. It produces tight dimensional accuracy and can cut complex contours that a wire saw can’t. But the recast layer is a real issue for metallographic work — it’s a thin zone of melted and re-solidified material with altered grain structure and composition. For tungsten sputtering targets, the copper contamination from the brass EDM wire electrode is a disqualifier in semiconductor applications. Diamond wire sawing avoids both problems.
Limitations of Wire Saw for Hard Metal Cutting
Cutting speed is slow. At 0.2–1.0 mm/min feed rate, these are not high-throughput operations. Cutting a 40 mm cross-section of Ti-6Al-4V takes 40–130 minutes. If you need to section hundreds of parts per day, conventional methods with post-processing will be faster overall.
Wire wear is higher on metals than on brittle materials. Titanium, tungsten, and molybdenum all cause faster diamond wire wear than glass, ceramics, or silicon. Expect wire replacement every 2–4 days of continuous cutting (8 hours/day), depending on material and cross-section size. For tungsten, wire life is shortest — the high hardness wears down the diamond coating faster. Budget for 전착 다이아몬드 와이어 루프 as a consumable cost, and track wire condition through regular tension calibration checks.
Straight cuts only. Unless you add a rotary axis (SG20-R supports this), the wire cuts in a straight line. Complex 3D profiles still require EDM or multi-axis CNC grinding.
Cross-section size constraints. The SG20 handles cross-sections up to about 80 mm. Larger billets need a bigger machine frame. For very large tungsten or titanium sections, discuss custom configurations with our engineering team.
실질적인 다음 단계
If you’re cutting titanium, tungsten, or molybdenum and the current method is costing you in tool wear, material waste, or post-cut surface prep time, send us test samples. We’ll run cuts at optimized parameters and return the pieces with measured Ra values, dimensional data, and cross-section photos. No charge for the first test run.
For the complete overview of diamond wire cutting across all metallic materials, see our hub page on 금속용 와이어 톱.
