Machine Tool Mastery: A Key Requirement for Mechanical Engineers
A proficient mechanical process engineer must be skilled in processing equipment application and possess comprehensive knowledge of the machinery industry.
A practical mechanical process engineer possesses a thorough understanding of various types of processing equipment, their applications, structural characteristics, and machining accuracy within the machinery industry. They can skillfully arrange specific equipment within their factories to optimize the layout for different processing parts and processes. Additionally, they are aware of their processing strengths and weaknesses and can effectively utilize their strengths while mitigating their weaknesses to coordinate the company’s machining work.
Let’s start by analyzing and understanding various processing equipment commonly used in the machining industry. This will give us a clear definition of the processing equipment from a practical standpoint. We will also analyze these processing equipment theoretically to better prepare for our future work and improve our skills. Our focus will be on the most common processing equipment such as turning, milling, planing, grinding, boring, drilling, and wire cutting. We will elaborate on the type, applications, structural characteristics, and machining accuracy of these processing equipment.
1. Lathe
1) The type of lathe
There are numerous types of lathes. According to a machining technician’s manual, there are up to 77 types. The more common categories include instrument lathes, single-axis automatic lathes, multi-axis automatic or semi-automatic lathes, return wheel or turret lathes, crankshaft and camshaft lathes, vertical lathes, floor and horizontal lathes, profiling and multi-tool lathes, axle roller ingots, and shovel tooth lathes. These categories are further divided into smaller classifications, resulting in varying numbers of types. In the machinery industry, vertical and horizontal lathes are the most commonly used types, and they can be found in almost every machining setting.
2) The processing scope of the lathe
We mainly select a few typical lathe types to describe the range of applications for machining.
A. A horizontal lathe is capable of turning internal and external cylindrical surfaces, conical surfaces, rotary surfaces, annular grooves, sections, and various threads. It can also perform processes such as drilling, reaming, tapping, threading, and knurling. Although ordinary horizontal lathes have low automation and involve more auxiliary time in the machining process, their wide processing range and overall good performance have led to widespread use in the machining industry. They are considered essential equipment in our machinery industry and are widely used for various machining operations.
B. Vertical lathes are suitable for processing various frame and shell parts, as well as for working on the inner and outer cylindrical surfaces, conical surfaces, end faces, grooves, cutting and drilling, expanding, reaming, and other part processes. With additional devices, they can also carry out threading, turning end faces, profiling, milling, and grinding processes.
3) The machining accuracy of the lathe
A. The usual horizontal lathe has the following machining accuracy: Roundness: 0.015mm; Cylindricity: 0.02/150mm; Flatness: 0.02/¢150mm; Surface roughness: 1.6Ra/μm.
B. The vertical lathe’s machining accuracy is as follows:
- Roundness: 0.02mm
- Cylindricity: 0.01mm
- Flatness: 0.03mm
Please note that these values are relative reference points. The actual machining accuracy can vary based on the manufacturer’s specifications and assembly conditions. However, regardless of the fluctuation, the machining accuracy must meet the national standard for this type of equipment. If the accuracy requirements are not met, the purchaser has the right to refuse acceptance and payment.
2. Milling machine
1) The type of milling machine
The different types of milling machines are quite diverse and complex. According to a machining technician’s manual, there are over 70 different kinds. However, the more common categories include instrument milling machines, cantilever and ram milling machines, gantry milling machines, plane milling machines, copy milling machines, vertical lifting table milling machines, horizontal lifting table milling machines, bed milling machines, and tool milling machines. These categories are further divided into many smaller classifications, each with varying numbers. In the machinery industry, the most commonly used types are the vertical machining center and the gantry machining center. These two types of milling machines are widely used in machining, and we will provide a general introduction and analysis of these two typical milling machines.
2) The scope of application of the milling machine
Due to the wide variety of milling machines and their different applications, we will focus on two popular types: vertical machining centers and gantry machining centers.
A vertical machining center is a vertical CNC milling machine with a tool magazine. Its main feature is the use of multi-edge rotary tools for cutting, which allows for a variety of surface processing, including plane, groove, tooth parts, and spiral surfaces. With the application of CNC technology, the processing range of this type of machine has been greatly improved. It can perform milling operations, as well as drilling, boring, reaming, and tapping, making it widely practical and popular.
B, gantry machining center: compared with the vertical machining center, the gantry machining center is the composite application of a CNC gantry milling machine plus tool magazine; in the processing range, the gantry machining center has almost all the processing capacity of the ordinary vertical machining center and can adapt to the processing of larger tools in the shape of the parts, and at the same time has a very big advantage in the processing efficiency and machining accuracy, especially the practical application of the five-axis linkage gantry machining center, its processing range has also been greatly improved, It has laid the foundation for the development of China’s manufacturing industry in the direction of high-precision.
3) The machining accuracy of the milling machine:
A. Vertical machining center:
Flatness: 0.025/300mm; Crude excess: 1.6Ra/μm.
B. Gantry machining center:
Flatness: 0.025/300mm; Surface roughness: 2.5Ra/μm.
The machining accuracy mentioned above is a relative reference value and does not guarantee that all milling machines will meet this standard. Many milling machine models may have some variation in their accuracy based on the manufacturer’s specifications and assembly conditions. However, regardless of the amount of variation, the machining accuracy must meet the national standard requirements for this type of equipment. If the purchased equipment does not meet the national standard’s accuracy requirements, the buyer has the right to reject acceptance and payment.
3. Planer
1) The type of planer
When it comes to lathes, milling machines, and planers, there are fewer types of planers. The machining technician’s manual states that there are approximately 21 types of planers, with the most common being cantilever planers, gantry planers, bullhead planers, edge and mold planers, and more. These categories are further divided into many specific types of planer products. The bullhead planer and gantry planer are the most widely used in the machinery industry. In the accompanying figure, we will provide a basic analysis and introduction to these two typical planers.
2) The scope of application of the planer
The planer’s cutting motion involves the back-and-forth linear movement of the workpiece being processed. It is best suited for shaping flat, angled, and curved surfaces. While it can handle various curved surfaces, its processing speed is limited due to its characteristics. During the return stroke, the planer cutter does not contribute to the processing, resulting in idle stroke loss and lower processing efficiency.
Advancements in numerical control and automation have led to the gradual replacement of planning methods. This type of processing equipment has yet to see significant upgrades or innovations, particularly when compared to the development of vertical machining centers, gantry machining centers, and the continuous improvement of processing tools. As a result, planers face tough competition and are considered relatively inefficient compared to modern alternatives.
3) The machining accuracy of the planer
The planning accuracy can generally reach the IT10-IT7 accuracy level. This is especially true for the processing of the long guide rail surface of some large machine tools. It can even replace the grinding process, which is known as the “fine planing instead of fine grinding” processing method.
4. Grinder
1) The type of grinding machine
Compared to other types of processing equipment, there are approximately 194 different types of grinding machines, as stated in a machining technician’s manual. These types include instrument grinders, cylindrical grinders, internal cylindrical grinders, coordinate grinders, guide rail grinders, cutter edge grinders, plane and face grinders, crankshaft/camshaft/spline/roll grinders, tool grinders, superfinishing machines, internal honing machines, cylindrical and other honing machines, polishing machines, belt polishing and grinding machines, tool grinding and grinding machine tools, indexable insert grinding machine tools, grinding machines, ball bearing ring groove grinding machines, roller bearing ring raceway grinding machines, bearing ring superfinishing machines, blade grinding machine tools, roller processing machine tools, steel ball processing machine tools, valve/piston/piston ring grinding machine tools, automobile/tractor grinding machine tools, and other types. Since the classification is extensive and many grinding machines are specific to certain industries, this article focuses on providing a basic introduction to the commonly used grinding machines in the machinery industry, specifically cylindrical grinding machines and surface grinding machines.
2) The scope of application of the grinding machine
A. A cylindrical grinding machine is primarily used to process the outer surface of cylindrical or conical shapes, as well as the end face of a shoulder. This machine offers excellent processing adaptability and machining accuracy. It is widely utilized in the processing of high-precision parts in machining, particularly in the final finishing process. This machine ensures geometric size accuracy and achieves superior surface finish requirements, making it an indispensable piece of equipment in the machining process.
B, The surface grinder is mainly used for processing plane, step surface, side, and other parts. It is widely used in the machinery industry, especially for processing high-precision parts. The grinding machine is essential for ensuring machining accuracy and is the last choice for many grinding operators. Most assembly personnel in equipment assembly industries are required to have the skill to use a surface grinder, as they are responsible for carrying out the grinding work of various adjustment pads in the assembly process using surface grinders.
3) The machining accuracy of the grinding machine
A. Machining accuracy of cylindrical grinding machine:
Roundness and cylindricity: 0.003mm, surface roughness: 0.32Ra/μm.
B. Machining accuracy of surface grinding machine:
Parallelism: 0.01/300mm; Surface roughness: 0.8Ra/μm.
From the above machining accuracy, we can also clearly see that compared with the previous lathe, milling machine, planer and other processing equipment, the grinding machine can achieve higher behavior tolerance accuracy and surface roughness, so in the finishing process of many parts, grinding machine is widely and widely used.
5. Boring machine
1) The type of boring machine
Compared with previous types of processing equipment, the boring machine is considered relatively specialized. According to machining technician statistics, there are approximately 23 types categorized as deep hole boring machine, coordinate boring machine, vertical boring machine, horizontal milling boring machine, fine boring machine, and boring machine for automobile tractor repair. The most commonly used boring machine in the machinery industry is the coordinate boring machine, which we will briefly introduce and analyze its characteristics.
2) The processing scope of the boring machine
There are various types of boring machines. In this brief introduction, we will focus on the coordinate boring machine. The coordinate boring machine is a precision machine tool with an accurate coordinate positioning device. It is mainly used for boring holes with precise size, shape, and position requirements. It can perform drilling, reaming, end facing, grooving, milling, coordinate measurement, precision scaling, marking, and other tasks. It offers a wide range of reliable processing capabilities.
With the rapid advancement of CNC technology, particularly CNC metal fabrication service and horizontal milling machines, the role of boring machines as the primary hole processing equipment is gradually being challenged. Nevertheless, there are certain irreplaceable aspects to these machines. Regardless of equipment obsolescence or advancement, progress is inevitable in the machining industry. It signifies technological advancement and improvement for our country’s manufacturing industry.
3) The machining accuracy of the boring machine
The coordinate boring machine generally has a hole diameter accuracy of IT6-7 and a surface roughness of 0.4-0.8Ra/μm. However, there is a significant issue in the boring machine’s processing, especially when dealing with cast iron parts; it’s known as “dirty work.” It can result in an unrecognizable, damaged surface, making it likely that the equipment will be replaced in the future due to practical concerns. After all, appearance matters, and while many may not prioritize it, we still need to maintain a facade of maintaining high standards.
6. a drilling machine
1) The type of drilling machine
The most commonly used equipment in the machinery industry is the drilling machine. Almost every machining factory will have at least one. With this equipment, it’s easier to claim that you’re in the machining business. According to a machining technician manual, there are about 38 different types of drilling machines, including coordinate boring drilling machines, deep hole drilling machines, radial drilling machines, desktop drilling machines, vertical drilling machines, horizontal drilling machines, milling drilling machines, center hole drilling machines, and more. The radial drilling machine is the most widely used in the machinery industry and is considered standard equipment for machining. With it, it’s nearly possible to operate in this industry. Therefore, let’s focus on introducing this type of drilling machine.
2) The scope of application of the drilling machine
The main purpose of the radial drill is to drill various types of holes. Additionally, it can also perform reaming, counterboring, tapping, and other processes. However, the machine’s hole position accuracy may not be very high. Therefore, for parts that require high precision in hole positioning, it is advisable to avoid using the drilling machine.
3) The machining accuracy of the drilling machine
Basically, there is no machining accuracy at all; it is just a drill.
7. Wire cutting
I have yet to gain much experience with wire-cutting processing equipment, so I haven’t accumulated a lot of knowledge in this area. Therefore, I have yet to do much research on it, and its use in the machinery industry is limited. However, it still holds unique value, especially for the blanking and processing of special-shaped parts. It has some relative advantages, but due to its low processing efficiency and the rapid development of laser machines, wire-cutting processing equipment is gradually being phased out in the industry.
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