Why do we recall brazed inserts of cemented carbide? In today’s era of rapid development in cutting tool technology, indexable inserts dominate the mainstream market with their convenience and versatility. However, the once-popular brazed carbide lathe bits have not faded into obscurity. This tool, which fixes a carbide insert to a steel shank via silver brazing, still shines in small workshops, tool rooms, and special processing scenarios thanks to its unique flexibility and cost-effectiveness. Today, we’ll explore its core features, usage techniques, and unique value.

What Are Brazed Carbide Inserts?

Brazed carbide inserts are one of the representatives of traditional cutting tools, with a core structure combining a “carbide insert + steel shank”. Through the silver soldered process, the high-hardness carbide insert is firmly fixed to the high-toughness steel shank, integrating the excellent wear resistance of carbide and the impact resistance of steel.

Compared with modern indexable inserts, the most obvious difference is that the insert and shank are inseparable. The surface is usually flat-top designed without preset chip breakers. Despite its seemingly simple structure, it can achieve diverse functions through post-grinding. Widely used in industrial lathes, Swiss-type cam screw machines and other equipment in the early years, it is no longer mainstream today but remains irreplaceable in specific scenarios.

Core Advantages: Why Are They Still Popular?

Controllable Cost and Outstanding Cost-Effectiveness

There’s no need for frequent insert replacement. After wear, it can be reused only by grinding and repairing, which greatly reduces tool consumption costs. It is a highly cost-effective choice for small-batch production or small workshops with limited budgets.

Strong Customization Capability

According to processing needs, any cutting angle, chip breaker, and tool tip shape can be ground with special grinding wheels. It can easily handle special processing scenarios that are difficult for indexable inserts to adapt to (such as deep hole drilling and special-shaped part cutting).

Adaptability to Special Scenarios

The shank can be cut, bent, or welded as needed, enabling it to “reach” processing areas that conventional inserts cannot. It is particularly suitable for matching old machine tools and customized fixtures.

Excellent Heat Dissipation Performance

Compared with the clamping design of indexable inserts, the brazed structure of the steel shank and carbide insert allows for smoother heat conduction. This helps reduce heat accumulation during cutting and improves processing stability.

Amid Soaring Tungsten and Cobalt Prices, Have Brazed Carbide Inserts Become a “Cost-Saving Tool”?

Since 2025, the prices of strategic minor metals such as tungsten and cobalt have entered a “soaring” mode—65% black tungsten concentrate has surged by 107% compared with the beginning of the year, tungsten powder prices have exceeded 92.9 US dollars per kilogram (converted at 1 US dollar ≈ 7 yuan), and cobalt powder has risen by as much as 194.1%. This price surge has put cost pressure on enterprises relying on indexable carbide inserts. Meanwhile, brazed carbide inserts, once regarded as “traditional tools”, have re-emerged as a preferred cost-saving option due to their characteristics of “reusability and low material loss”.

Why Are Brazed Inserts More Resistant to Price Increases?

To understand the cost advantage of brazed inserts, we first need to compare the difference in “material utilization rate” between them and indexable inserts:

Indexable Inserts

The insert is a standardized prefabricated part. After wear, the entire insert needs to be replaced. The remaining unworn part (accounting for about 30%-50% of the total insert weight) is scrapped along with the old insert, which means part of the tungsten and cobalt materials is wasted every time it is replaced. Moreover, affected by the rising prices of tungsten and cobalt, the purchase price of a single insert has generally increased by more than 100% compared with the beginning of the year.

Brazed Carbide Inserts

The insert is fixed to the steel shank via silver brazing. After wear, only the cutting edge needs to be ground and repaired for reuse, without replacing the entire insert. Taking common external turning tools as an example, a single brazed insert can have a service life 3-5 times that of an indexable insert of the same specification through multiple grindings, significantly reducing the consumption of carbide materials.

Practical Case Study

A small machinery factory processes 45# steel workpieces. Originally using indexable inserts, it consumed 20 inserts per month with a unit purchase price of 11.2 US dollars (after the surge in tungsten and cobalt prices), resulting in a monthly tool cost of 224 US dollars. After switching to brazed inserts of the same material, it only needs to purchase 5 brazed inserts per month (unit price 16.9 US dollars). With grinding and repair, the monthly tool cost is reduced to 84.5 US dollars, saving 62.5% of costs per month.

Cost Reduction Through Three Links: “Selection, Usage, and Repair”

Against the backdrop of high tungsten and cobalt prices, to maximize the cost advantage of brazed carbide inserts, it is necessary to grasp three key links: “appropriate selection, standardized usage, and efficient repair”, avoiding material waste or shortened service life due to improper operation.

Selection: Precisely Match Processing Needs to Avoid “Over-Engineering”

The tungsten and cobalt content directly determines the cost of brazed inserts (the higher the cobalt content, the higher the cost). During selection, it is necessary to “choose on demand” according to processing materials and working conditions, without blindly pursuing high specifications:

Processing Ordinary Steel/Cast Iron

Select low-cobalt carbide (e.g., Co content 6%-8%) to balance wear resistance and cost. Avoid using high-cobalt alloys with Co content above 10% (the cost of high-cobalt alloys has increased by more than 190% compared with the beginning of the year, and they are not recommended unless necessary).

Processing Stainless Steel/High-Temperature Alloys

If high toughness is required, alloys with Co content 8%-10% can be selected. However, priority should be given to improving performance through “optimizing welding processes + edge strengthening” rather than simply relying on high-cobalt materials.

Shank Reuse

Prioritize the use of versatile standard steel shanks (e.g., 45# steel, 40Cr). After the insert is worn, only the insert needs to be replaced, and the shank can be reused for welding, reducing steel waste (the cost of the steel shank is only 1/20 of that of carbide, with high reuse value).

Meanwhile, referring to the suggestions from Zhuzhou Meetyou Cemented Carbide: Select a suitable tool groove according to the insert shape and tool geometric parameters to ensure the insert is firmly fixed during welding. This avoids early damage to the insert caused by welding deviations and indirectly reduces material consumption.

Usage: Standardize Operations to Reduce Wear and Extend Grinding Cycles

The service life of brazed inserts is directly related to usage habits. Standardized operations can reduce unnecessary wear, extend the interval between each grinding, and further reduce material consumption:

Control Cutting Parameters

Avoid overloading (e.g., excessively high cutting speed and feed rate), which will cause rapid wear of the insert and increase grinding frequency. For example, when processing aluminum alloys, the cutting speed is recommended to be controlled at 150-200m/min, and the feed rate at 0.1-0.2mm/r, ensuring both efficiency and reduced insert wear.

Optimize Installation Methods

Minimize the extension length of the insert from the tool post (it is recommended not to exceed twice the diameter of the shank) to avoid insert chipping caused by vibration. If a longer extension is required, auxiliary support for the tool post can be used to improve rigidity.

Reasonable Use of Coolant

For processing scenarios prone to high temperatures (such as milling and deep hole drilling), spray coolant in a timely manner to reduce the temperature of the insert, minimizing thermal deformation and thermal cracks (thermal cracks will render the insert irreparable and directly scrapped).

Repair: Efficient Grinding + Welding Reuse to Maximize Material Value

The core cost-saving advantage of brazed inserts lies in their “repairability”. Establishing efficient grinding and secondary welding processes can increase the material utilization rate of the insert to over 80%:

Selection of Grinding Tools

Use green silicon carbide wheels or diamond wheels (refer to suggestions from the Practical Machinist forum). Avoid white aluminum oxide wheels (which cannot effectively grind carbide and are prone to causing overheating and cracking of the insert). Control the grinding wheel speed during grinding (recommended 2000-3000r/min) to avoid rapid cooling and heating, reducing grinding cracks (grinding cracks will lead to insert scrapping and material waste).

Secondary Welding Techniques

When the insert is worn to the point where it cannot be ground, the steel shank can be reused through “debrazing – cleaning – rewelding”. Note the following during welding:

Use industrial borax as a flux (dehydrate and crush in advance to remove impurities) to ensure welding strength and avoid insert detachment due to incomplete welding.

When welding high-titanium, low-cobalt, fine-grain alloys, use 0.2-0.5mm mesh compensation gaskets (recommended by both Zhuzhou Jintai and Badou Library) to reduce welding stress and the risk of insert cracking (welding cracks will lead to insert scrapping and loss of carbide materials).

Edge Grinding

After regrinding, grind the edge and tool tip fillet with an oilstone (grain size 800-1200 mesh) to improve edge smoothness and extend service life by 20%-30%, indirectly reducing grinding frequency and material loss.

Suitable Scenarios: When Are Brazed Inserts Most Cost-Effective?

Not all scenarios are suitable for brazed tips. Amid high tungsten and cobalt prices, the following scenarios offer the highest cost-effectiveness:

Small-Batch, Multi-Variety Processing

No need for frequent insert replacement. Grinding and repair can adapt to different workpieces, avoiding the problem of “waste after insert replacement” with indexable inserts.

Adaptation to Old Machine Tools

Traditional lathes and milling machines without quick-change tool posts can use brazed inserts without equipment modification, saving equipment upgrade costs.

Special Processing Needs

Such as deep hole drilling and special-shaped part cutting. Custom insert shapes can be ground to avoid purchasing special indexable inserts (the price of special inserts is more than 50% higher than that of general-purpose inserts).

For mass standardized production (such as auto parts processing), if an automated tool change system is already in place, a compromise solution of “brazed inserts + indexable tool post modification” can be adopted: install brazed inserts on indexable tool posts to balance the efficiency of automation and the low-cost advantage of brazed inserts.

निष्कर्ष

Against the backdrop of persistently high tungsten and cobalt prices, the “reusability” of brazed carbide tips precisely addresses the core of cost reduction—”reducing material consumption”. Through “precise selection, standardized usage, and efficient repair”, enterprises can not only reduce tool procurement costs but also reduce dependence on high-priced tungsten and cobalt materials.

For small and medium-sized manufacturers or enterprises with limited budgets, instead of passively bearing the pressure of rising indexable insert prices, it is better to re-examine the value of this “classic tool”. After all, in an era sensitive to costs, “what is saved is what is earned”. Have you already used brazed inserts to reduce costs? Welcome to share your practical experience in the comment section!