How Robots and Additive Manufacturing Work Together

Fig. 2—High speed machining with a tool path derived from NURBS interpolation results in a faster, smoother and more accurate finish. NURBS-based solids may be a “glamorous” Carbide Aluminum Inserts feature, but not all PC CAM users will find it helpful.

Fig. 1—Solid modeling is a software feature now offered by many PC CAM products. This display illustrates a CAD model that was imported and utilized to model mold components.

Fig. 3—When part geometry is modified, associativity allows the tool path to be updated quickly and easily. Not all PC CAM products offer the same degree of associativity, so usefulness varies from product to product.

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The evolution of PC CAM is marching along. Originally, PC CAM was a technical product. Purchase decisions could be based on easy-to-understand technical issues. Today, PC CAM is represented by sophisticated products that are increasingly hard for buyers to tell apart. As a result, many PC CAM buyers will base their decisions on complex issues that do not address their everyday NC programming needs. Tungsten Carbide Inserts Understanding the current PC CAM market can help you do a better job of selecting the best PC CAM system for your needs.

PC CAM is a product, and just like all products it has a life cycle. This life cycle goes through several phases that are common for any product being sold today. Marketing professionals spend a lot of time and money tracking products through these phases. How a product is presented and sold changes as it matures.

Phase 1: Introduction

When a new type of product is introduced, it is technically very different from other alternatives a buyer might have at that time to fill the same need. When the first television was introduced, it was a radically different from other home entertainment equipment, such as the radio and the phonograph. There were few competitors, and innovative people rushed to buy them, regardless of price. At this phase of the product introduction, the technical differences are obvious and easy to understand.

PC CAM began life in the early 80s in response to a market demand for NC programming tools—tools more affordable and accessible than the comprehensive, yet very expensive, CAD/CAM systems of the day. Insightful evaluation questions were: “Can you program a mill?” or “Can you run on my PC?” One PC CAM product might be based on a typed language, another might be based on graphics. The differences between the few early PC CAM products were simple, obvious and easy to understand.

Phase 2: Growth

In this phase, more competitors begin offering similar products, and the price comes down. More people understand the value of the products and buy them. Toward the end of the Growth phase, even the conservative personality types are buying the product. The products become similar and harder to tell apart based on features.

The introduction of MS DOS was the first major event in the Growth phase of PC CAM. It allowed products to run on everyone’s computers. MS Windows gave it another boost. But Windows also started the current commonality of interfaces among PC CAM software, with all products starting to look alike. Since 1993, the PC CAM market has experienced good growth through increased acceptance from the machining community.

Phase 3. Maturity

In the product maturity phase, just about everybody who wants one has one. There are many brands to choose from, all with seemingly similar features. In the TV marketplace, for example, there are many brands to choose from, and while there are still feature differences, most people will find just about any brand acceptable. In fact, most buyers neither understand the technical differences between individual features, nor appreciate their value. Advertising and marketing become key to the financial success of a product as consumers rely on brand recognition to guide their purchasing decisions.

Currently we are entering the Maturity phase of the PC CAM life cycle. This may last a long time, as there doesn’t seem to be a replacement technology on the horizon. The percentage of customers buying their first CAM system continues to fall, indicating a high level of PC CAM acceptance. There are many PC CAM brands to choose from, and these products continue to look more alike. Fewer customers seem to understand the importance of key features, while all products appear to claim a similar broad set of features.

Phase 4. Decline

The last phase occurs when a replacement technology has been introduced that slowly replaces the market demand for the original product. For example, radio sales declined after the introduction of the television set. This phase, however, appears to be many years into the future for the PC CAM market.

The PC CAM Buying Decision Today

So, how does knowing that PC CAM is in its mature market help you to make an intelligent buying decision today? There are four categories of issues to consider when buying a CAM system.

1. Features

In a mature market, features are less significant in differentiating the different brands of product. Your primary goal is probably to program your parts well with your people, not to own a specific software feature. You still have to understand and evaluate the important features. You also have to determine the quality and usability of the feature in a specific PC CAM package. Let’s look at some of today’s popular features.

Solid modeling. Solid modeling is the ability to work with, create, and machine solid models (Figure 1, above right). A solid model is the current standard in design CAD systems and is supported by several PC CAM products. It is a very significant technology for PC CAM, especially for companies working from their customers’ CAD data. Unfortunately, simply having “solids” says nothing about the quality of functionality provided. A solid modeler may be a “check box” feature, meaning a first release feature of limited functionality, or it may be the best thing since sliced bread. (You probably wouldn’t know, however, that solid modeling provides less functionality for those who program from 2D drawings or from wireframe IGES files.) It can provide all types of users with improved part visualization, better setup sheet graphics, and in some software, higher levels of automated programming.NURBS output. A new control feature from Fanuc and Siemens allows faster, smoother machining of 3D surfaces (Figure 2, at right). You have to have the right control and the right parts for this to be useful.Associativity. This is a general term that implies that different types of data associations are maintained automatically by the software. Change a tool size, and get a new tool path automatically, and so on (Figure 3, below right). This can be quite useful if fully supported. What you should really care about is not a yes/no answer to “associativity,” but rather how easily and readily you can make changes to your CNC program, especially the changes related to a part design change. A personal demo of your parts on the software being evaluated is often the only way to accurately access the true usefulness of a program’s associativity.Windows interface. Because all Windows users recognize the basics of a Windows interface, it is useful in reducing training times. This is a common feature today.Ease-of-use. Ease-of-use is a highly subjective issue but easily the single most important one. It’s not really a product feature, as much as it is the summation of all user interactions with the software.Ease-of-use covers four areas: ease-of-learning, intuitiveness, efficiency and functionality.

If you can sit down with a new software package and make a part in the first hour, without training, then that product is easy to learn for you. When you can figure out how to do what you want, and it makes “sense,” then it is intuitive for you. If you can make your part programs faster than with other products, then the software is “efficient” for you. Finally, if a software package has the real features needed to accomplish your part programs, then you have ease-of use through “functionality.” Nothing is harder than trying to program a part with a PC CAM product not capable of the task. All of these factors combine into “ease-of-use.”

The key point in looking at program features is that virtually all PC CAM systems list the same set of features, making them rather useless for product differentiation. Unfortunately, you can’t determine quality, integration, usability or completeness from a list.

2. Usability

Because you can’t tell PC CAM products apart by simply looking at their feature lists, what can you do? You can evaluate a product’s usability. This simply means that you have your people evaluate doing your parts on a specific PC CAM product. This evaluation will automatically include the features that your parts need, as well as demonstrate the program’s general ease-of-use.

Can your people learn and use the product being evaluated? Can the software efficiently program your parts? You can’t go wrong evaluating your parts and your people against a PC CAM product, since you are evaluating the most important issues you have.

How can you do this?

Idea #1: After you have narrowed your choices to a few likely candidates, you can ask two salesmen of different products to program the same part, side-by-side. This can help you see the differences in how the two products will be used. Remember that you are also watching the differences in the two demonstrators. A good “demo jock” (professional demonstrator of a specific software) can make any software look good. For that reason, time trials with demo jocks aren‘t recommended.

While the time to program is interesting, large time differences are often due to the proficiency of the demo jock, not the software. Skilled and experienced users can make any software easy. Instead, spend more time seeing if you can follow the demonstrator’s steps and understand what he or she is doing. Counting the steps or keystrokes is useful because you will have to replicate these actions to be successful with the software.

Idea #2: Same as #1 above, but ask to do a part yourself. Use a simple part. The purpose of this exercise is not to validate advanced features. The purpose is to give you a better idea of how you will like using the software. Let the demo jock guide and assist you. But again, keep track of how many actions you had to perform, and how well you understood them. How much guidance did you need?

If you simply become the hands for the demo jock who directs every detailed action, and are lost trying to follow the demo, this is probably not a good CAM system for you. On the other hand, if you only need moderate guidance and it makes sense to you, it is probably a good choice for you.

Idea #3: Buy a product. You can’t really know a product well until you have used it for a while. You can look for companies that have a 100 percent money back guarantee. This policy lets you use the product for a couple of months. If it doesn’t work well for you, you get your money back.

3. Service and Support

If you fail to have a clear winner after your Usability evaluation, other important factors need to be considered. You will probably need service and support for whatever product you select. Whether it’s training, phone support, post processors, or new improved software in the future, you should give the edge to the company that provides these services best. A good product without support will be an unwise purchase.

A common question is, What should service and support cost? This question is a good one, because service and support often represent a big part of your cash-out-of-pocket, and aren’t typically part of the software purchase price. Support and services come from two primary sources, the PC CAM reseller and the PC CAM developer. In theory, the reseller services are more personal and more expensive. On the other hand, a PC CAM company has greater resources than the typical reseller, and it may offer a variety of “factory” service options in addition to those offered by a reseller.

Nothing is free. Everybody involved with selling PC CAM is in it for the profit, as in any other business. They need to be paid for their time. So how can services be offered for free? There are many different situations. Sometimes a well-intentioned small CAM reseller offers free services to close a sale. The problem occurs when the reseller later discovers the resources to deliver these services aren’t available, or discovers that working for free is no way to stay in business.

The better situation is where the free services are actually being paid for, buried in the price of the software. The greatest problem you’re likely to have is not whether you lose $500 in promised services, but whether you have a CNC machine sitting idle, missing a job delivery date due to unavailable services. These costs will quickly exceed the actual cash cost of the service. Your first priority should be making certain that the service and support you need will be available. The actual price (assuming that it is reasonable) is of secondary importance.

Here are some real world examples. The only CAM company I have accurate details for is my own, but they will give you an idea of what to expect. The two most important services customers need are training and prompt qualified phone support. At least 90 percent of our customers program their first parts before formal training. Probably only 25 percent of our customers seek formal training. Phone support is widely used by these customers, especially within the first weeks after purchase. After the first few weeks, phone calls diminish rapidly, as the user becomes competent and successful with the product.

The following representative examples are based on data from Gibbs resellers and the Gibbs factory.

Training by typical resellers: A day of onsite training goes for between $500 to $1,000, plus expenses. This training can be tailored to the needs of the customer and can include a number of people.Phone support from typical reseller: Most resellers will take a telephone tech support call from a customer. But most do not have full time telephone support staff standing by. This means that the time- to-reply can vary greatly from minutes to days. A few resellers do have full time tech support staff and typically charge a fee for phone support to cover the cost of these individuals.Training by the factory: Classes are offered on site for $250/day (including lunch). A basic milling class takes 2 days.Phone support by the factory: Offered free. A staff of technicians is assigned to this job only. Costs are spread out over all sales to provide a high level of user service.Software maintenance option: A charge of 10 percent of the software price is applied as an annual fee to customers who always want the latest improvements. One or two new versions a year are offered. This lets a customer avoid having to buy a newer version of software in the future.

While every CAM company is different, these details should give you an idea of the types of services that you should evaluate and consider.

4. Full Cost

Notice that cost, not price, is the last issue to consider. Unlike a television, the purchase price of PC CAM software is probably the least important cost to consider with your purchase. Of greater significance is the value, or cost, of your time. Your full cost will include time spent evaluating products, time spent learning the product, extra time spent programming because you picked a poor product, and machine time wasted due to programming time or errors.

Let’s say you value a programmer at $30/hour. If you have him or her spend 10 hours evaluating each of five PC CAM products, you have just spent $1,500 for this assignment. If one PC CAM system requires 40 hours less training to get started, you will save $1,200 per person trained over the life of the product. Let’s value your CNC machine at $100/hour. If one PC CAM system allows you to write programs faster with fewer errors, you will waste less machine time. An hour per week would be $5,200 per year per machine. The differences in PC CAM products can be a lot more than one hour per week.

These machine and personnel costs are typically several times larger than the purchase price of the PC CAM software. What is the cost of training? Phone support? New versions of software? Cost is certainly an important issue, but you need to look past the purchase price, which is only one part of your total cost.

Beyond The Feature List

Even though the current crop of PC CAM products looks similar, there are still significant differences that should be important in making your purchase decision. Skimming the feature list and moving on to evaluating ease-of-use, usability, service, support, and cost, will dodge the traps and lead you to a good purchase decision.

The Carbide Inserts Website: https://www.estoolcarbide.com/product/vnmg-carbide-inserts-for-cast-iron-turning-inserts-p-1184/

latheinserts June 30, 2023

Multiaxis Machining： Definition & Different Types of Machines

Boom and bust. Boom and bust. If you have been involved in metalworking and the machine tool industry long enough to have endured and persevered through several of these boom-bust cycles, then you probably have this sense that the difference between the boom and the bust has increased over a time. In other words, the peaks have seemed higher and the dips deeper with each passing cycle.

Well, this is not all in your head or your gut. This impression is real.

I have spent the last 10 years attempting to forecast the metalworking industry, particularly machine tool consumption. It didn’t take me long to understand that metalworking and machine tools are the classic example of a cyclical, boom-bust industry. Although I was armed with that knowledge and had the data to back it up, I was nonetheless surprised when I took a fresh look at the long-term global machine tool consumption data from Gardner Business Intelligence’s latest World Machine Tool Survey.

Chart 1 in the slideshow at the top of this article shows world machine tool consumption with a theoretical maximum consumption trend. Notice the gray line. It represents global consumption in U.S. dollars, adjusted for inflation. This line indicates that the increase in global consumption over time is caused by more countries becoming industrialized and not the weakening of the U.S. dollar through inflation.

From 1960 to 1970, global machine tool consumption increased in an almost perfectly straight line. To almost anyone in the metalworking industry today, an entire decade of straight-line growth is almost beyond imagination. However, the boom-bust cycle that seems normal today did not begin until 1971.

Generally, a complete cycle in machine tool consumption has taken 10 years from peak to peak. In recent years, when interest rates were lowered to nearly zero (and in some cases below zero), the cycle periods became less regular.

In fact, the height of peak consumption in those cycles increased over time, even though the periodicity (peak-to-peak time) did not. The dotted blue line in this chart represents a theoretical maximum consumption of machine tools. It is based on the straight-line growth of recorded machine tool consumption from 1960 to 1970. In other words, we can suppose that the straight-line growth during this period was the natural or “organic” pattern for machine tool consumption and that the forces behind it were normal and steady (at least in theory). Given this assumption, machine tool consumption can be theorized to “max out” at points on this line in the period after 1970 as a logical supposition. This theoretical maximum gives us a useful reference for examining the actual consumption results. 

In fact, the peaks of machine tool consumption generally fall on that line. We had no such peak in the late 1990s (thank you, dot-com bubble), and we dramatically overshot the theoretical maximum machine tool consumption in 2008 and 2011-2012 (more on that later).

This theoretical maximum can be compared to the bottom of each machine tool cycle. For example, in 1971, the theoretical maximum machine tool consumption was slightly more than $30.3 billion, but actual machine tool consumption was only $26.7 billion. So, at the trough of the cycle, consumption fell short of the Cutting Tool Inserts theoretical maximum by $3.6 billion, or 12 percent. History shows that, cycle after cycle, this shortfall has widened.

Table 1 in the slideshow at the top of this article shows that the cycles were indeed getting worse, both in terms of the absolute distance from theoretical maximum and the percentage below the theoretical maximum. Note that, even though the size of the shortfall gap grew in 2002, the shortfall represented a slightly smaller percentage of the theoretical maximum than in 1994. Then, in 2009, the shortfall decreased significantly, and with it, the percentage of the theoretical maximum naturally decreased as well.

The fact that the last two dips in machine tool consumption have not been as severe and the fact that machine tool consumption dramatically overshot the theoretical maximum in 2008 and 2011-20Milling inserts 12 are related. Both developments were caused by China’s influence on the global market.

The gray line in Chart 2 shows world machine tool consumption, while the blue line shows world machine tool consumption with figures from China dropped from the calculation. Notice that, until the mid 2000s, there was not a significant difference between the two lines. That’s because China only accounted for no more than 15 percent of global consumption before that period. By 2011, China’s machine tool consumption accounted for 40 percent of the global total.

Therefore, it seems clear that the influence of China’s suddenly huge appetite for machine tools is the reason the troughs have been less severe and the peaks have been higher than expected. Chart 3 shows world machine tool consumption and the theoretical maximum machine tool consumption without including numbers from China. Through 1990, the peaks continued to hit the line while China still represented a small percent of global consumption. Then, in 2008, instead of dramatically overshooting the theoretical maximum, as might be expected, peak consumption fell well short of this line. Missing this level had never happened before. Likewise in 2009, the trough is much deeper both in an absolute sense and in comparison to the theoretical maximum. Instead of the expected $19.9 billion shortfall, the shortfall in global machine tool consumption widened to $41.1 billion, a figure much larger than in 1994 and 2002. And, without the numbers from China, the percent shortfall increased to 51 percent from 25 percent.

All of the factors that help explain why China’s surge in machine tool consumption had this effect may be impossible to identify. However, I believe that two known factors provide a reasonable explanation.

First, extremely low interest rates enabled global manufacturing companies to build new factories anywhere in the world in order to exploit low labor costs. Near-zero interest rates meant that financing new capital equipment was virtually free. So why not put that new capital equipment where labor costs were relatively low compared to Western manufacturing countries? As a result, low global interest rates magnified China’s machine tool consumption over that from any other country.

Second, more than any other country in the world, China represents a distinctly two-sided, yet lop-sided, machine tool market. High-end manufacturing with high-end machine tools is one side. Much of this capability is concentrated in the electronics and automotive sectors. In contrast, the other side of the market consists of low-end, even manual, machine tools. This side of the market is much larger than the high-end side, and it is this lopsided low end of the market that made it appear that the troughs in global machine tool consumption were less severe. It also is this low end of the market that made it appear that global machine tool consumption was overshooting its theoretical maximum.

This is not the end of the story. Simply taking China’s machine tool consumption from the calculations does not lead to an entirely accurate analysis. The high-end manufacturing taking place in China represents a growing percentage of the Chinese metalworking and machine tool industry. One way to capture the size of this high-end industry is to focus on Chinese imports of machine tools. It stands to reason that these imports are more sophisticated machines being installed by global manufacturers and high-end Chinese job shops.

Chart 4 has insights to offer here. The gray line shows global machine tool consumption with only Chinese machine tool imports included in the data. It is significant that this method of analysis shows that global machine tool consumption falls almost exactly as expected on the line of the theoretical maximum. Therefore, true global machine tool consumption falls somewhere between the gray and blue lines of chart 2.

How does this understanding shape our outlook for the future of world machine consumption?

Chart 4 shows that global machine tool consumption in 2016 was $30.1 billion, or 33 percent below the theoretical maximum. This shows that the global manufacturing industry has not yet recovered from the great recession of 2008 to the extent expected. I forecast that global consumption will increase in 2017, even though many major national economies are still working through significant debt issues.

“The Fourth Turning,” an excellent book on long-term cyclical forecasting by William Strauss and Neil Howe, describes a theory that I believe applies to machine tool boom-bust cycles. Based on this book’s theory, the current cycle in our industry should bottom out between 2020 and 2025. Accordingly, we should see a dip in global machine tool consumption during those years.

Ultimately though, this dip may not be much deeper than current global machine tool consumption. In the last few cycles, the troughs in machine tool sales have been bottoming out at about 40 percent below the theoretical maximum. Based on a theoretical maximum consumption of $95.3 billion in 2020, the low point of global consumption would be about $57.2 billion.

Once a cycle bottoms out, machine tool consumption tends to grow for six or seven years. If we hit bottom in 2020, then we should hit the next peak between 2025 and 2030. Based on the trend that began in 1960, we can expect machine tool consumption to peak somewhere near $100 billion between 2025 and 2030.

Of course, these expectations are speculative. Many unforeseeable events may alter the situation. Nevertheless, insights into the long-term growth trend in machine tool consumption, the cyclical nature of the industry and what is happening in China can help us understand these shifts and their implications as they occur.

About the Survey

This is the 51st edition of an independent annual survey that collects statistics from machine tool consuming and producing countries and compares them in real U.S. dollars. It is conducted through the research department of Gardner Business Media Inc. (Cincinnati, Ohio) by Steve Kline, director of market intelligence. Data for this report comes from research conducted by Gardner Business Intelligence.

Traditionally, Gardner collected actual or estimated data on production, exports and imports from 26 countries. However, beginning with the 2015 survey, actual import and export data were included for every country that imported at least $100 million of machine tools in at least one year since 2001. This change added 34 more countries to the overall survey. For these additional countries, production was estimated, although in a few instances actual production data was found on government websites.

Consumption is calculated by adding imports to and subtracting exports from production figures. The data typically are reported in local currencies, then converted to U.S. dollars. After this conversion, all of the data in this latest survey also were adjusted for inflation using the Bureau of Labor Statistics’ Producer Price Index for capital equipment. This adjustment promotes a more accurate historical comparison.

Sources of Data

Special assistance came from the 15-member CECIMO consortium (Brussels, Belgium) and AMT—The Association For Manufacturing Technology (McLean, Virginia). Also, for countries that did not report, import and export data was gathered from the International Trade Centre (intracen.org).

Definitions

A machine tool is usually defined as a power-driven machine, not portable by hand and powered by an external source of energy. It is designed specifically for metalworking either by cutting, forming, physical-chemical processing or a combination of these techniques.

Machine tools are traditionally broken down into two categories: metalcutting and metal forming. Metalcutting machines typically cut away chips or swarf and include (but are not limited to) broaching machines, drilling machines, electrical-discharge machines, lasers, gear-cutting machines, grinders, machining centers, milling machines, transfer machines and turning machines such as lathes. Metal-forming machines typically squeeze metal into shape and include (but are not limited to) bending machines, cold-heading machines, presses, shears, coil slitters and stamping machines.

Data presented in the World Machine Tool Survey are solicited for metalcutting machines (codes 8456-8461 under the Harmonized Tariff System) and for metal-forming machines (8462-8463), and are solicited for complete machines only, not including parts or rebuilt machines.

Exchange Rates

All data reported in domestic currencies are translated into U.S. dollars using the average daily exchange rate for the year (not the end-of-year rate) as reported at Moody’s Analytics. All analysis is done in real U.S. dollars.

Shipments vs. Orders

In addition to contributing statistics to this survey, many countries also track orders for new machine tools. These are, by their nature, different sets of numbers, and they may or may not be related. This survey is based on actual shipments of new machine tools from the factories in which they are produced. In contrast, the various order compilations in individual countries around the world are based on bookings for machines that will be shipped in the future. The time lag between these two events can vary greatly. An in-stock lathe might be shipped one day after the order is placed, whereas a complex engine-machining line might take a year to be delivered after the order has been received. On average in the U.S., orders lead shipments by four to five months. That is likely a common lead time for other countries as well.

The Carbide Inserts Website: https://www.estoolcarbide.com/tungsten-carbide-inserts/

latheinserts June 26, 2023

The Efficacy of Carbon Component on WC tic co cemented Carbide

WC Co cemented carbides are easy to oxidize and decompose in high temperature application, which have many problems, such as brittleness, brittle fracture, processing softening and edge breaking, etc. they are still not suitable for high speed cutting of steel, so they have great limitations. WC tic co cemented carbides are known to have wear resistance, oxidation resistance and crater wear resistance.

However, due to the fact that tic and its solid solution are much more brittle than WC, this alloy also has relatively large defects, that is, the toughness and weldability of the alloy are poor. Moreover, when the content of TiC exceeds 18%, the alloy is not only brittle, but also difficult to weld. In addition, tic can not significantly improve the high temperature performance.

TAC can not only improve the oxidation resistance of cemented carbide, but also inhibit the grain growth of WC and tic. It is a practical carbide which can improve the strength of cemented carbide without reducing the wear resistance of cemented carbide. TAC can increase the strength of cemented carbide by adding TAC into WC tic co cemented carbide The addition of TAC helps to reduce the friction coefficient, thus reducing the temperature of the tool. The alloy can bear a large impact load at the cutting temperature. The melting point of TAC is as high as 3880 ℃. The addition of TAC is very beneficial to improve the high temperature performance of the alloy. Even at 1000 ℃, it can still maintain a good hardness and strength.

Tic and TAC are insoluble in WC, while WC is soluble in tic. The solubility of WC in the continuous solid solution formed by TAC is about 70wt%. The solubility of WC in the solid solution decreases with the increase of TAC content. The properties of WC tic tac Co alloys are mainly achieved by adjusting the tic + TAC, the ratio of Ti atom number to ta atom number and the content of cobalt. When the ratio of Ti atom number to ta atom number and the content of cobalt are fixed, adjusting the content of TiC + TAC to achieve the best performance has become the focus of research.

1. The raw materials used in this experiment are: WC powder, compound carbide powder [(W, Ti, TA) C] powder and Co powder. The chemical composition and average particle size are shown in Table 1.

Table 1 Composition and average particle size of raw materials

After the powder is proportioned according to the standard table 2, it is milled and mixed on nd7-2l planetary ball mill for 34h, the mass ratio of the ball material is 5:1, the grinding medium is alcohol, the adding amount is 450ml / kg, the milling speed is 228r / min, and 2wt% paraffin is added four hours before the end of the milling. The slurry shall be screened (325 mesh), vacuum dried, screened (150 mesh) and pressed to shape after drying, the pressing pressure shall be 250Mpa, and the blank size shall be (25 × 8 × 6.5) mm. The pressed samples were sintered in vsf-223 vacuum sintering furnace at 1420 ℃ for 1H.

Table 2 composition ratio of alloy%

The three-point bending method was used to determine the bending strength of the sintered sample on sgy-50000 digital compression strength tester. The final strength data was the average value of three samples. The hardness HRA of the sample was measured on the Rockwell hardness tester. The diamond cone indenter with a load of 600N and a cone angle of 120 ° was used.

The cobalt magnetism is measured by the cobalt magnetic tester, and the coercive force is measured by the coercive force meter. After the surface of the sample is grounded into a mirror surface, the mirror surface is corroded by the equal volume mixture of 20% sodium hydroxide solution and 20% potassium cyanide solution, and then the metallurgical observation is performed on the scanning electron microscope at 4000 times. Magnetic properties magnetic properties include co magnetic com and coercive force HC. Com represents the carbon content in the alloy, HC represents the grain size of WC. According to the national standard gb3848-1983, the cobalt magnetism and coercive force of the alloy are determined, and the results are shown in Table 3. It can be seen from table 3 that the relative magnetic saturation COM / CO and coercive force HC decrease with the increase of the content of compound carbide (W, Ti, TA) C.

Table 3 test results of cobalt magnetism and coercive force of tungsten cobalt titanate

Generally speaking, the control of COM content over 85% of cobalt to ensure that the alloy does not decarburize, the COM / CO ratio in group 1 is far lower than 85%, and its HC is also abnormally high. The non-magnetic η phase (co3w3c) appears in the alloy, which belongs to the serious deodorization structure. Therefore, we will only discuss groups 2, 3 and 4:

In this experiment, the total carbon content of the 2, 3 and 4 groups of alloy is 7.18wt%, 7.61wt%, 8.04wt%, the total carbon content increases in turn, and the HC decreases in turn. The size of coercive force is related to the dispersing degree of cobalt phase and carbon content of the alloy. The higher the dispersing degree of cobalt phase is, the greater the coercive force of the alloy is. The dispersing degree of cobalt phase depends on the cobalt content and WC grain size of the alloy. When the cobalt content is determined, the finer the WC grain is, the higher the coercive force is. Therefore, HC can be used as an index to indirectly measure the WC grain size

The content of carbon affects the solid solution of tungsten in cobalt. With the increase of carbon content, the content of tungsten in cobalt phase decreases. The solid solution of tungsten in cobalt is 4wt% in carbon rich alloy and 16wt% in carbon deficient alloy. As w can inhibit the dissolution and precipitation of WC in γ phase, WC is refined and HC is high, so the total carbon content increases in turn, WC grain coarsens and HC decreases. 2.2 the hardness and bending strength test results of the influence of the micro-structure on the mechanical properties of the alloy are shown in Figure 1. The bending strength increases with the increase of the C content of the compound carbide (W, Ti, TA), while the hardness is the opposite.

Fig. 1 hardness and bending strength test results of tungsten cobalt titanate

With the decrease of C content in the compound carbides (W, Ti, TA), HC increases, that is, WC grain refinement. The hardness increases with the refinement of WC grains when the cobalt content is constant. This is because the alloy is strengthened through the grain boundary and phase boundary, and the refinement of carbide grain will increase its solubility in the bonding phase, and the hardness of γ phase will also be increased, which will lead to the increase of the hardness of the whole alloy.

However, the effect of WC grain size on fracture toughness is more complex. For the alloy with grain size smaller than sub micron, the main indentation cracks are crack (intergranular) deflection and toughness bridging, with a small amount of transgranular fracture.

As the WC particle size becomes finer, the probability of defects in the grains decreases, and the strength of the particles increases, resulting in the decrease of transgranular fracture and the increase of intergranular fracture. For the alloy with large grain size, there are only four independent slip systems in the WC crystal. With the increase of WC grain size, the deflection and bifurcation of the crack increase, resulting in the increase of fracture surface area and toughening. Therefore, it is not accurate to judge the bending strength by grain size alone, and its microstructure should also be analyzed.

The metallurgical structure of cemented carbide with four different compound carbides (W, Ti, TA) C content is shown in Figure 2. With the increase of (W, Ti, TA) C content, the shape of WC tends to be regular. Most of WC in Figure 2a are irregular long bars arranged intensively. The average grain size of WC is relatively fine, but its adjacent degree is high, which is caused by the insufficient crystallization of WC, the cobalt phase does not completely wrap WC and the thickness is uneven. And there are coarse triangular WC grains. When η phase decomposes, CO is precipitated, resulting in local co enrichment. At the same time, W and C precipitate on the surrounding WC grains to form coarse triangular WC grains. From figure 2a-2d, it can be seen that the shape, size and distribution of WC grains have obvious changes. WC grains tend to regular plate shape, the coarsening adjacency of grains decreases, and the average free path λ of bonding phase increases. In Figure 2D, WC grains are well developed, with narrow particle size distribution, low coarse adjacent degree of grains, large average free path λ of bonding phase, most of which are about 1.0 μ m plate WC, and a small amount of triangle WC around 200nm, all of which are dispersion distribution.

Fig. 2 metallographic picture of C content of different compound carbides (W, Ti, TA) in cemented carbide

The dissolution precipitation of WC occurs in the sintering process, which makes the WC with higher energy (small particles, edges and corners of particle surface, bulges and contact points) dissolve preferentially, and makes the WC dissolved in liquid phase deposit on the surface of large WC after precipitation, which makes the small WC disappear and the large WC increase, and makes the particles accumulate more tightly depending on the shape adaptation, makes the particle surface tend to be smooth, and makes the two WCS The distance between them is shortened.

In the sintering process of low cobalt alloy, with the increase of total carbon content, the amount of liquid phase and the retention time of liquid phase increase, WC dissolution precipitation process is more full, WC grains develop completely, the surface is more smooth, and the particle size distribution is more uniform. In addition, with the increase of the total carbon content of the alloy, the solid solution of W in CO decreases, and the decrease of W content in the bonding phase will improve the plasticity of the bonding phase, thus increasing the bending strength of the cemented carbide. Therefore, the bending strength increases with the increase of total carbon content.

conclusion

(1) When the content of TNGG Insert CO is constant, with the increase of compound carbide (W, Ti, TA) C content, the total carbon content of the alloy increases, HC decreases, WC grain coarsens, w solution in CO decreases, and the hardness of the alloy decreases.

(2) The metallographic structure of the alloy is closely related to the total carbon content of the alloy. The compound carbide (W, Ti, TA) C content increases, the total carbon content of the alloy increases, the WC grain adjacency decreases, the particle size distribution narrows, the average free path λ of the bonding phase increases, and the bending strength increases.

(3) The best microstructure and properties of wcta are as follows: when the total carbon content is 8.04wt%, the hardness is 91.9hra, and the bending VBMT Insert strength is 1108mpa.

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latheinserts June 16, 2023