Month: February 2020

As technology advances and revolutionizes engineering and machinery, you want to know you’re using the best equipment and leading your business forward. Some of these advancements are in computer numeric control (CNC) machining and 3D printing. They both work with different materials. But which one is best for your needs?

CNC machining and 3D printing have similarities and differences, and each has unique benefits. They have varying circumstances where you would want to use them regarding cost and availability. Breaking down each manufacturing style will help you pick the best method for you and your business.

Their main differences occur in production, waste, scale, material availability and size of the parts.

SIMILARITIES BETWEEN CNC AND ADDITIVE MANUFACTURING (3D PRINTING)

CNC machining and additive manufacturing are both computer-controlled solutions to making products out of a given material. They’re both machines at the forefront of building technology safely and efficiently.

As machinists and engineers want to build a prototype, a part or a custom product, they can turn to one of these machines to do the job for them. As long as the machines have the design, you don’t have to worry about human error because the machines are automated. While this doesn’t mean issues don’t arise, there’s more consistency with production and less chance of injury.

There is some overlap with these two manufacturing methods. Some CNC machines can use STL and OBJ files, which 3D printers also accept.

CNC machinery is older than 3D printing and still has a stronger foothold in manufacturing. The form started in the 1940s and had molded to fit into the industry up to the present. 3D printing came along in 1986. It’s still relatively new and evolving to be more accessible and versatile. 3D printing can help in some areas of prototyping, but it’s not a replacement tool for CNC machining.

They’re not so much alternatives to the other as they are both aspects of the manufacturing world. They meet different demands and handle different materials and markets. CNC machines and 3D printing both have unique capabilities and constraints that suit them for specific jobs. As they fit their niches in the market, you’ll want to compare it to whatever industry you’re in.

DIFFERENCES BETWEEN CNC MACHINING AND 3D PRINTING

From their building methods to what applications they can handle, CNC machining and 3D printing offer creative solutions in vastly different ways. Finding out their differences and strengths will help you find which one is right for you and your business.

3D printers are typically more efficient than traditional manufacturing. The printer uses the materials that make up the item it’s creating, whereas traditional manufacturing methods such as CNC Machining require more materials for the mold to work. On average, 3D printers produce less waste than traditional manufacturing methods.

However, when production is large-scale, traditional manufacturing methods have a distinct advantage. Assembly lines are faster than a 3D printer in mass production because printers build layer by layer. In the hours that it could take to 3D print a product, an assembly line could have mass-produced hundreds of the same product.

Additionally, 3D printers can only use the area of the printing bed for making parts. Large-scale parts might not fit in that space. While the parts can be broken down into smaller pieces 3D printers can build, that might not be cost-effective and will take time. Traditional manufacturing has the advantage of the assembly line’s labor and will be able to produce items on a larger scale. Future 3D printers could be able to build larger items, but not on the level of what CNC machines offer with regard to quality and quantity.

3D printers can manipulate different materials such as plastics, metals and polymers. However:

• Not all 3D printers can use these materials. It takes separate machines for each material.
• 3D printers cannot work with every material that traditional manufacturers use due to high melting points.
• Some projects might not be able to consider using 3D printers if they require specific materials that are incompatible with the printers.

Here is the bottom line — 3D printing won’t replace traditional manufacturing because of its disadvantages in mass-produced items.

3D Printing vs. Traditional Manufacturing

CNC machining starts with a block of material and shapes it with a rotating tool. Following the program, it carves away excess until you have the finished product. This is the subtractive method because it’s taking away material.

3D printing layers on material in the additive method that builds your design. Both ways have pros and cons in terms of durability, precision and use of materials.

Material Usage for CNC and 3D

CNC machining works with a variety of materials. They can use:

• Metal alloys
• Woods
• Acrylic
• Modeling foam
• Thermoplastics
• Machining wax

CNC machines have heating systems that can manage heavy materials. These materials are used to build substantial parts for engines, aircraft and other machines. They need to be exact, dependable and durable. The cutting tools for the design might have to switch, but most tools are standardized to fit any CNC machine.

3D printing doesn’t have this variety, using materials like plastics or resins. They can’t produce items strong enough to withstand intense environments like airplanes or other machinery. Also, 3D printers can’t switch between materials. Certain 3D printers are for specific kinds of material.

3D and CNC Precision of Production

CNC machining is more precise and consistent than 3D printing because they have a higher tolerance for heat. 3D printers end up with distorted products when there’s too much heat. They can offer precision but cannot remain consistent. 3D printers are often regarded as more user-friendly than CNC machines, but when they malfunction, someone has to troubleshoot them because the fault means production of unusable products.

CNC and 3D Speed of Production

CNC is a faster solution than 3D printing. Automated CNC machines can work around the clock as long as they’re properly maintained. A project that could take CNC machining an hour would equate to a 3D printer taking hours to get the final product because it has to build the product layer by layer. A 3D printer’s pace might have to slow down during the process to get the design right. Different 3D printers could also be programmed with specific speeds that you can’t alter. It depends on the machine you use.

3D printed products also require work after they’re built. The products need to be washed, polished and sealed before people can use the product. This could extend prototype testing to a longer time period with a lot of waiting in between. 3D printers are also popular for smaller, custom-manufactured items. But if you have to wait for the item to be built and still do a lot of work post-print, you lose a lot of time before you can move the product.

Versatility of Machinery for CNC vs. 3D

CNC machines can produce fixtures, tools and custom-designed parts. They have a wide range of quality settings so you can make a prototype that has a rougher design in some areas and perfect in others so you can test that part.

When testing prototypes for a project, a CNC machine could quickly build a design so the developers can test it. 3D printers don’t have these kinds of options. It will slowly shape the design as it was programmed. Accuracy is key when constructing a final product, but when time is a constraint and you want to test some prototypes, 3D printers can slow down you and your project. Designs made for a CNC machine usually can’t be substituted with a 3D printer because the products are voluminous and it would take hours for a 3D printer to finish them.

Noise and Mess Produced by CNC and 3D

These differences relate to the subtractive and additive methods. CNC machining is much more noisy and messy than 3D printing because it uses a tool to cut away material. This creates noise and a lot of scrap metal or wood shavings. CNC machines cause a lot of vibrations, so they need to be in a space where they won’t bother anyone. 3D printing only uses the material it needs for the product. There’s little to no waste, and the printers don’t vibrate like a CNC machine.

Applications for CNC and 3D

CNC machining can manufacture bigger products and can handle heat-resistance. 3D printing has more niche categories, such as printing food or working in space.

CNC Machining vs. 3D Printing

According to World Finance, 3D printing is not a solution that can replace CNC machining. 3D printing is a part of the manufacturing world, but it’s not the invention that’s going to change the market as everyone knows it.

3D printers can improve certain aspects of manufacturing but cannot handle the whole market, as CNC machining still works better in many situations. CNC machining still offers better quality than expensive 3D printers.

On a smaller production scale, 3D printers have an edge in saving businesses money from buying expensive molds. They also offer an insight to the product’s shape and aesthetic. But as production increases and time factors in, they don’t hold up as well as CNC machines.

BENEFITS OF CNC MACHINING OVER 3D PRINTING

CNC machining fits with mass production. It can create many products in a shorter period, where 3D printing would take hours to create one product. That’s just one advantage of CNC. Let’s take a look at some others.

Prototyping Becomes Easier

CNC machines are better for prototypes that can withstand structural tests because they carve the design from the material. They can also build prototypes out of the exact material that will be used to make the final product.

Structural tests and alterations will be more accurate because they use the same material. This could speed up the production process because the changes will be to the design and not the material. 3D printers don’t fabricate prototypes with the structural strength, so they can’t conduct physical tests.

Prototype Integrity Improves

CNC machines don’t heat the material and reform it. The material stays stronger and has a better structural integrity than 3D printers, which have to heat the material to build the intended product. 3D printers might also have to add foreign materials to the mixture to be able to make the prototype, which CNC machines don’t need.

Surface Finish Advantage

CNC machines provide better surface finish than 3D printing because the materials don’t deform during the process. The rigid material and cutting action keeps the product together and has fewer chances for mistakes or deformations to occur. 3D printing has poorer surface finish. The material bends, warps or distorts because the material is layered heated plastic.

Tolerance Levels Rise

CNC machines work with higher precision, so the parts have a better tolerance than 3D printers. Because of tolerance level, prototypes that have shafts or connect to other parts will be higher quality and will more likely fit with other components.

Price and Volume Don’t Dictate Price

3D printing costs depend on the volume of needed materials. Final product volume doesn’t dictate the price for CNC machines. 3D printing wouldn’t be cost-effective with larger orders, and this is the situation where CNC machines thrive.

Quality in Favor of CNC

Larger layers from a 3D printer are faster but not as high-quality as smaller layers. If you need a prototype, you have a choice to get it fast but of slightly less quality, or wait longer for the prototype with the best quality the printer can provide. CNC machines have the option for you to choose resolutions for your item. They can offer varying qualities in a short amount of time, making them ideal for quick builds and immediate results for testing.

Keeping Costs Down

If you have the option of choosing which manufacturing method to use for your product, CNC machining is usually cheaper than 3D printing.

Contact  Kaito mould Works, Inc., for Your CNC Machining Needs

CNC machining can build the parts you need for your business. Our expert machinists at Kaito Mould Works, Inc., will provide outstanding work that will help you reach your goals. We aim to help you get the correct part for your project.

Kaito Mould Works, Inc., provides services for custom machine building, precision parts machine and reverse engineering of components to give you the product you need promptly. We deliver exceptional CNC machining solutions for manufacturers in multiple industries. Our skill in specialization and dedication to our work will help you and your business stay on the cutting edge of the industry. We have the solutions you need. Get in touch with us today.

If we can help you with your project please call us at 0086-769-82821468 or email sales@kaitomould.com.

Electrical discharge machining (EDM) is a manufacturing process that implements electrical sparks to form a metal shape. Because of these sparks, EDM is also sometimes referred to as spark machining. In this process, the desired shape is cut from the metal when current discharges, or sparks, occur between two electrodes; where the sparking occurs, cuts are made into the metal, creating the desired shape and detaching it from the metal sheet.

There are two main types of EDM — wire and sinker — and several other less common methods, but this article will be focusing on wire EDM. Wire EDM uses a wire as the tool electrode. The wire is wound between two spools and, when in motion, the active part of the wire continually switches — preventing the material from eroding from the wire itself.

UNDERSTANDING THE EDM PROCESS

During the EDM process, a metal part is placed into dielectric fluid, and a wire is fed through the submerged metal component. An electric current is sent through the part to create the sparks that will ultimately help form the desired shape of the component.

When the distance separating the electrodes narrows, it increases the intensity of the electric field, and thus increases the strength of the dielectric fluid. The current more easily passes between the two electrodes under these conditions, leading to the separation of the component from the metal sheet with each spark.

After the currents have passed through and the desired shape has been achieved, manufacturers will sometimes perform a process called “flushing,” using a dielectric liquid to help remove any leftover material or waste from the finished product.

BENEFITS AND APPLICATIONS OF WIRE EDM

The wire EDM machine, also known as a “cheese cutter,” offers several unique advantages, making it a popular choice for manufacturers across a range of different industries.

EDM Benefits

Wire EDM machines are able to carefully remove excess material without exerting a strong cutting force. The process is often automated, meaning it has less chance of causing damage to the workpiece itself. And because wire EDM machines can accommodate hard materials, there is no need for secondary, post-machining thermal treatments. As a result, there is little to no heat stress placed on the shaped part, and less chance that the surface of the part will become distorted.

EDM Applications

Wire EDM is most commonly used in mold and die manufacturing processes, particularly for extrusion dies and blanking punches. EDM can be used in everything from prototypes to full production runs, and is most often used to manufacture metal components and tools. The process is best suited for applications requiring low levels of residual stress.

EDM Industries

EDM is most commonly used to manufacture parts and components for the automotive, aerospace, and electronics industries.

UNIQUE ADVANTAGES OF WORKING WITH WIRE EDM

EDM offers many unique advantages, making it the go-to machining process for producing a variety of different parts and components. First off, EDM’s high precision allows it to create very complex shapes. And its ability to work with hard materials means that it can bring those materials to close tolerances as needed.

Since EDM can handle a high level of complexity, the process can be used to create very small, intricate pieces. And with no direct contact occurring between the tool and the actual part being shaped, it’s easier to achieve a smooth surface finish that is accurate and burr-free.

And, perhaps most importantly in some instances, parts manufactured through EDM are ready for use immediately upon completion of the EDM process.

Why Use EDM?

So, why use EDM?

• EDM can work hard materials and alloys of increasing thickness without compromising the surface finish of the resulting product.
• As a noncontact machining process, EDM can achieve high-quality finishes, thereby reducing the need for post-processing procedures and surface treatments, which are often necessary with other manufacturing processes.
• Because EDM is a computer numerical controlled (CNC) machining process and uses automated software to program functions, the process produces accurate, predictable, and repeatable results during every production run.
• Wire EDM can also accommodate small production runs requiring tight tolerances, as is often the case in the aerospace and medical equipment industries.
• Wire EDM is more cost-effective and time-efficient than other processes available.

Wire EDM Services at Kaito MouldWorks

Here at Kaito Mould  Works, Inc., we’re proud to specialize in custom machinery and precision parts. Our team is highly experienced in all aspects of wire EDM, and we have the in-house capabilities to perform EDM services on a wide variety of parts and components.

To learn more, check out our EDM machining page or contact the team today.

If we can help you with your project please call us at 0086-769-82821468 or email sales@kaitomould.com.

When a manufacturing business doesn’t have specific in-house CNC machining abilities, they’ll contract these tasks out to other companies to save money and time. Costs for in-house machining include expensive equipment, experienced workers, and space to house the new operation. In contrast, contract manufacturing can be done with the same level of quality and more reasonable expenditures.

In contract CNC machining, a business that specializes in efficient production of parts uses the hiring company’s designs to create the project. This frees up more of the hiring company’s time and resources to grow their business or focus on their essential manufacturing processes rather than spending time learning new equipment. Components are then labeled with the hiring company’s brand.

Many industries use contract CNC machining services for production of medical devices, electronics, parts for aerospace and defense, and packaging. The extent of the contract manufacturing can be limited to one small part or can be an entire product line.

Benefits of Contracting CNC Machining

• Expertise: The outsourcing company does not have to start from scratch and get up to speed with production of a new part or product. They rely on experienced veterans who are accustomed to making new components with tight tolerances and exact specifications.
• Equipment: The cost of even one CNC machine is high and may not make financial sense if it is used to produce only a few parts.
• Ability to Scale Up: If more parts are suddenly needed due to increased industry or marketplace demand, contract machining firms are better able to take on the extra work than if the outsourcing company had to purchase new machines, train new employees, and devote more floor space to manufacturing. Outsourcing smaller runs of parts also allows the original manufacturer to focus attention on the most important parts and products that bring in the most business.
• Quality Control: Contract CNC machining must be done to tight tolerances and meet or exceed customer expectations. Many contract companies have excellent in-house quality control and related certifications that prove their expertise. In addition, most contract firms have a range of people on staff to assist the outsourcing team with designing the most efficient and effective parts.

Circumstances to Contract CNC Machining

Some manufacturers may still be uncertain as to whether outsourcing is the best solution. Under some circumstances, contracting CNC machining work is an easy decision to make. Businesses that face the below challenges are best suited for outsourcing their work:

• Inability to Add New Equipment: The cost, the operation, and the housing of adding new CNC machinery are all challenges to smaller and mid-sized firms that have a core business.
• Production Range Is Narrow: Companies that specialize in one type of part may want to outsource needed components outside of this one area.
• Schedules and Demand Changes Frequently: Some manufacturers have more seasonal demand, or the nature of their industries mean that demand fluctuates. Scaling up and down can be expensive. Outsourcing makes these changes in demand easier to manage.
• Supply Chain Is Especially Complex: Contract manufacturing helps simplify your processes.

Any time a company’s core strengths could be diluted by adding new capabilities in-house, it is worth considering the value of contract manufacturing. Contract CNC machining benefits manufacturers of medical devices, aerospace and defense components, packing, and electronics.

Kaito Mould  Works for Your Contract Manufacturing

Kaito Mould Works has capacity for contract manufacturing for many industries including Medical, Pharmaceutical, Energy, Food Processing, Government/Military, Aerospace, Electronics, Telecommunications, Packaging, and Industrial.

Our contract CNC machining services include lathing, milling, and turning on multiple axis. Finishing services can be customized to produce completed parts that are ready to go. We continually invest in our machinery and utilize state-of-the-art technologies that improve efficiency and effectiveness for our customers. We are SO 9001 / AS9100 certified, ensuring the attention to quality and detail required by the industries we work with.

If we can help you with your project please call us at 0086-769-82821468 or email sales@kaitomould.com.

To Our Valued Customers:

Each year as the calendar turns, we try to utilize this season as a time of reflection and communication with our customer base.

This is a moment for us to offer commentary on the events and accomplishments of the preceding year and to say “Thank You” for the trust and confidence that our customers place in us daily.

2019 proved to be another year of aggressive continuous improvement resulting in enhancements across the entire organization. We completed a major office expansion, allowing all nine of our project managers to come together in one collaborative environment. Our project managers act as the “inside sales” contact for our customers and with this additional space are now situated strategically for better customer service as all team members work together to facilitate projects and schedules on your behalf. We have also invested in additional large milling equipment to complement our five-axis gantry mill. Large scale machining is a service offering that has seen continuous demand causing constraints a significant percentage of the time. As a result, we have installed yet another large bridge mill with a size capacity of approximately eight feet (Y axis) by ten feet (X axis) by four feet (Z axis) to provide the additional capacity that our customers have been requesting. In addition, a host of supplementary improvements have also been made to internal processes and systems with an emphasis on high performance workflow.

We have just completed our 2020 Roadmap which represents our internal business plan and includes strategic goals and initiatives for continuous improvement for the upcoming year. Succession planning has been at the forefront at Kaito Mould Works as we strive to keep Kaito Mould  growing and thriving well into the future. As a result, our current plan involves building depth and developing additional bench strength in each department and across the entire organization. We place great value on the “people” side of our business and each year spend time and energy nurturing our culture, including our values, vision and mission to heighten employee engagement and to optimize our overall organizational health. This year will be no exception and will again bring record amounts of employee training, coaching and mentoring across our entire roster. The objective is, and always will be, to provide complete customer satisfaction by supplying products and services which meet or exceed customer requirements. Consequently, our team members are the key ingredient to making that happen on a continuous basis and therefore warrant additional investment each and every year.

As 2020 commences, we are embarking on this year from a position of strength with the wind at our backs having these enhancements fully implemented and contributing to our organization on a regular basis. Strong momentum from the previous year and a sizeable backlog help put us in an excellent position right out of the gate. We now turn our attention to the upcoming year as we consider additional areas of improvement to enrich the array of services that we can supply our expanding customer base. As always, we will be considering additional capacity increases and expanding capabilities whenever possible to better serve our clients. This year will bring many enhancements as our reinvestment plan has been set and will include many ancillary improvements such as inspection equipment, software purchases and upgrades, improvements to logistics, marketing and our overall working environment.

Regardless of the current events worldwide including trade wars, tariffs, trade agreements, geopolitical risks and regional unrest, we strive to keep our eye on the ball, which is our customer. You are our focus and have our unwavering support regardless of happenings around the world.

In conclusion, we say from our team to yours; “We look very forward to providing continued support to our existing and future customer base with this team in the upcoming year”. Thank you all for a great and memorable 2019!

We wish continued growth and prosperity to you and your organization and look forward to working with you again in 2020!

If we can help you with your project please call us at 0086-769-82821468 or email sales@kaitomould.com.

Stainless steel offers many benefits, from an attractive finish to high strength and durability. But those come at a cost for the machine and its operator. Steel can be a formidable opponent due to its strength and durability, but those features are what make it so useful in the first place. Between alloys, speeds and tool selection, many aspects will affect your final product and the process by which you create it.

Machining steel parts takes a certain level of preparedness and understanding of the materials you’re working with. Below are some of our tips for machining steel.

MACHINING PROCESS FOR STEEL

When machining stainless steel, you’ll have to take into consideration all of its characteristics. Remember that it is strong, even at high temperatures.

1. Endmills

The tools you use will have a major impact on your project and the damage it can cause to your machine. The ideal type of endmill varies by application, but be sure to stick with a high-speed steel or carbide-constructed tool. High-speed steels include tungsten and molybdenum. Cemented carbides are a good choice when you need higher feeds or speeds. Make sure the cutting tool is sharp and in good condition to keep a high quality of cut.

• Roughing: An endmill with 4-5 flutes can offer sufficient roughing on steel. Remember that higher flutes make room for higher feed rates.
• Slotting: To slot steel, you’ll have to be aware of chip control and take enough care so your tools aren’t chewed up and your finish isn’t ruined. Try a four-flute endmill, which allows for chips to leave the cutting area more efficiently.
• Finishing: To finish steel parts, you’ll want a large number of flutes or high helix of over 40 degrees.

2. Feeds and Speeds

Now that you have the right tool selected, you need to ensure your speeds are appropriate. While it takes a little fine-tuning, a good starting point would be between 100 and 300 surface feet per minute (SFM) with chiploads ranging depending on the tool size.

STEEL MACHINING TIPS

Steel can be tricky to machine, but it’s not too bad if you are prepared and use the right settings and tools. Be sure to keep these concepts in mind as you machine steel.

• Keep heat low: Steel machining can generate very high temperatures, so take precautions to minimize their effects. Be sure to use a cutting fluid. Between work hardening and low thermal conductivity, keeping heat away from the cutting area is important to keep it in top shape. If excessive heat remains here, you may see distortion and a reduction in corrosion resistance. Cutting fluids help provide lubrication to wash away any chips, lower the wear on your tools and cool the endmill down. Common cutting fluids include mineral oils and emulsifiable oils. Make sure that you have plenty to use because any interruption of the coolant can lead to fluctuations in temperature, which can affect tool life.
• Avoid work hardening: Many steels have high work hardening tendencies. Make sure your tools are sharp and try to keep it moving to avoid any lulls in the cutting process that would lead to a buildup of heat.
• Control vibration: The strength of stainless steel and the speed it requires from the tool can cause extensive vibrations. Vibrations on your work surface can damage your finish while adding wear to your tool. You’ll need a robust, rigid tool capable of high-speed cuttings. Keep your workpiece firmly in place with clamps and minimize any tool overhang. You can also try using tools with a small nose radius.
• Know your material: Every steel alloy is a little different. Know the properties of the one you’re using so you can better adjust your machine to address its characteristics. The addition of sulfur, for instance, can allow for higher feeds by affecting the hardening of chips and helping the tool edge stay consistent. Lead allows for higher speeds since it provides a lubricating property that keeps the heat down.

HOW IS MACHINING STEEL DIFFERENT THAN OTHER MATERIALS?

When machining steel, you’re not working with just one element. Steel is an alloy, comprised of carbon and iron, though other elements are often added to impart specific properties on the metals. This means that different types of steel are going to behave in different ways, and you have a lot of options. According to the World Steel Association, there are over 3,500 different grades of steel.

Alloys tend to have added strength from the inclusion of elements like nickel, chromium and copper. They may also improve its corrosion resistance, strength, ductility and ease of machining. Stainless steels use a larger amount of chromium to offer corrosion resistance. Some types of steel are even designed for easier machinability.

As for other metals, here is a breakdown of some of the more common options.

• Aluminum: In terms of machining steel vs. aluminum, the primary benefit of aluminum is that it is much lighter than steel. Aluminum also allows for faster machining, but it lacks the hardness and strength that steel has.
• Titanium: Titanium is one of the strongest metals out there, even in extreme or fluctuating temperatures. Plus, it has a low weight. The biggest trade-off is the cost of titanium, which is typically considerably higher than that of steel. Titanium is often chosen for sensitive applications like those in aerospace and defense.

COMMON STEEL MACHINING APPLICATIONS

Steel has a lot going for it in terms of strength and durability, but the biggest drawback is its weight. It typically is reserved for applications where weight isn’t much of a concern. This often includes structural components. Infrastructure like railways, buildings and roads commonly use steel. Other pieces like screws and bolts may also be made of steel. You can find it in industries like mining, shipbuilding and aerospace technology.

You may find stainless steel in even more places due to its attractive finish. It is versatile and common in furniture and appliances. The corrosion resistance of stainless steel also helps in these applications.

BOOST YOUR STEEL MACHINING PROCESS

Whatever the application, the proper approach can make all the difference in your steel machining process. If you adopt high-quality tools and efficient practices, steel doesn’t need to be a tough opponent. Make things easier for your machine operators and minimize expenses associated with quickly worn tools and ruined workpieces.

Contact the experts at Kaito Mould Works for more information on how you can improve your steel machining process today. With over 35 years of experience, we’ve got the knowledge and knowhow to bring your machining capabilities to the next level.

If we can help you with your project please call us at 0086-769-82821468 or email sales@kaitomould.com.