Ceramics is one of the most used materials in the modern world. It has wide applications in pottery, household utensils, appliances, and parts. Ceramic items are made by using different methods in several steps. Most industrial, electrical, and medical ceramic products are built by machining.
Ceramic machining is a manufacturing technique of different ceramic components by removing material from unfinished ceramic products. It is a complex production procedure that requires specialized processes and tools. Machining ensures tight tolerance, a finely finished surface, a complex shape, and precise dimensions of the components.
Let’s dive into the deep details of ceramic product manufacturing and ceramic machining.
What is Machining?
Machining is the manufacturing procedure of precisely shaped parts and components by cutting and removing materials from a raw product. It is a subtracting manufacturing method using machine tools. Machining is most often used in metal appliance manufacturing.
But, it can also be used in making ceramics, plastics, wood, and composite products.
What is Ceramic Machining?
Ceramic machining is the ceramic components-making process using machining tools and techniques. It cuts a raw ceramic element to give it a designated shape and dimensions.
There are different ceramic machining methods such as grinding, drilling, milling, turning, laser machining, surface grinding, CNC machining, chemical machining, diamond tooling, etc.
Grinding, drilling, and milling are the most popular ceramic machining techniques. Ceramics are hard and brittle materials, they require extra care to avoid any breaks or cracks during machining.
How is Ceramic Products Made?
Ceramic components are made in several steps. Here is the step-by-step process of making ceramic items.
Step 1: Raw Materials Selection
Ceramic product manufacturing starts with the raw materials selection. The materials are selected based on the desired properties of the final product.
Step 2: Materials Mixing
The selected ceramic materials are prepared and mixed in this stage. Here the raw materials are grinded into a fine powder and then mixed with water and necessary chemicals. After the mixing operation, the mixture becomes a semi-liquid slurry.
Step 3: Product Forming
The mixed ceramic slurry is formed in the desired shape of the final components at this step. Different ceramic forming techniques and tools are used here such as slip casting, injection molding, extrusion, and dry pressing.
Step 4: Drying
Raw ceramic products are dried here by controlled air, microwaves, and a heat chamber. The dried products become free from unwanted moisture and prepare for firing.
Step 4: Sintering or Firing
Sintering solidifies the dried ceramic products maintaining the desired shape. The shaped product is hardened at around 1000 degrees centigrade(°C) or 1832 degrees Fahrenheit(°F ).
The ceramic materials melt in the sintering method but the structure does not change. The sintering process is done in two consecutive steps: bisque firing and glaze firing.
Bisque Firing:
Bisque firing transforms unfired clay into durable, hard, and porous ceramics. The clay is placed in a kiln and slowly heated to 1742°F. This heating process removes the existing water, organic matter, and carbon compounds from the clay.
The sintered or bisque-fired components are hard and less fragile, but porous enough to apply glazes. It is then slowly cooled down to the normal temperature to avoid any breakage due to the abrupt temperature changes. The bisque-fired product is also known as bisque ware.
Glaze Firing:
The glaze firing is done after applying the glazed materials to the bisque ware. Here it is fired at high temperatures to melt and bond the glaze. Glaze firing improves the properties, color, and appearance of the product.
Step 5: Finishing
The glaze-fired hard ceramic items are refined in the finishing process to meet the specified shape, dimension, and tolerance of the product.
The machining, polishing, and coating are done on the ceramic products as the refining process.
Step 6: Quality Check
Finally, the ceramic products are checked by the quality control team to identify and separate the faulty pieces.
Different Methods of Ceramic Machining:
Machining is the most expensive step in the ceramics product manufacturing process. It may require 50% to 90% of the total costs.
The efficiency of ceramic machining is calculated by its MRR(material removal rate). It is the amount of ceramic materials removed per minute from a product surface. However, there are different ceramic machining methods. We are covering the most important three here.
Grind Machining or Grinding: Ceramic grind machining or grinding is the mechanical process of removing material from ceramic parts using rotating abrasive wheels. The purpose of grinding is to remove burrs and create a smooth finish.
The different grinding methods include surface grinding, cylindrical grinding, internal grinding, centerless grinding, and form (plunge) grinding.
Milling Machining:
The milling machine process is similar to drilling where a rotary milling tool is used to cut the material in a controlled way. The modern machine milling process works with a CNC(Computer Numerical Control) for automatic control over the manufacturing process.
Machine milling started to replace manual milling or hand filling at the beginning of the 19th century. The milling machine was operated manually until the mid-20th century. Then it was paired with the CNC technology in the 1950s, when computer technology arrived. That was the beginning of the modern automated machine milling process.
The revolving cutting instrument is the main part of a milling machine. This tool draws out the material from the part to give it a pre-designed shape. Milling machines use multi-point and single-point cutting tools as their cutting instruments.
Milling is done in several stages such as workpiece loading➜ tool selection➜ machine setup➜ milling execution➜roughing➜semi-finishing➜finishing ➜unloading➜inspection ➜quality control ➜ and post-processing.
Different types of machine milling processes are available to accomplish the milling operations such as face milling and end milling. The face milling is used to cut the surface and the end milling is used to cut the interior of the parts.
Some other machine milling processes include:
- Chamfer milling,
- Slot milling,
- Peripheral milling,
- Climb milling,
- Profile milling,
- Helical milling,
- Plunge milling,
- Thread milling
- And CNC milling.
Ceramic CNC Machining: Ceramic CNC machining is a computer-controlled ceramic manufacturing method. It is used to cut and shape ceramic materials into precise components. The CNC machine works according to the CAD(computer-aided) design.
But the CAD design first needs to convert into CNC machine-readable code i.e. CAM code. The CAM(computer-aided manufacturing) software program primarily converts the CAD design into CAM code. Then the CAM code is sent to the CNC machine. The CNC works on the CAM code to make the desired shape of the ceramic products.
Ceramic CNC machining is better than traditional machining due to its accuracy and control. It can cut the brittle and hard materials more accurately than other ceramic machining.
FAQs
What is green machining?
Green machining is the process of chip removal from advanced ceramic products at raw or unfired conditions. It is done with conventional ceramic machining tools made of steel, stainless steel, and carbon steel. It is a cost effective machining technique.
The green body machining is applied to the ceramic part that has gone through the bisque firing. The bisque process converts the unfired clay into durable porous ceramic. The bisque ceramic elements are not fully densified.
What is full density ceramic machining?
Full-density machining is the cutting process of fully densified fired ceramic products. It is a more challenging technique than green machining. It requires specialized and durable ceramic machining tools like diamond cutters.
Is it possible to machine ceramic?
Yes, it is possible to machine ceramic by using different machining processes and cutting tools. The tungsten carbide and diamond-made cutting tools are effective ceramic cutting instruments.
They can cut and remove any ceramic products to give them precise shapes, dimensions, and sizes. Yet, sufficient cautionary measures are essential when using ceramic machining tools to avoid chipping and cracking.
What are the 5 types of ceramics?
The five basic ceramics are structural, refractory, electrical, magnetic, and abrasive. Each ceramic has separate characteristics and functions. Porcelain, alumina, stoneware, ball clay, earthenware, silicon carbide, and zirconia, are some popular ceramics materials used for different purposes.
What is a milling grinder?
The milling grinder is a machine used to break solid materials into smaller pieces by cutting, crushing, and grinding.
What are 7 uses of ceramics?
The seven most common uses of ceramic materials are in construction, refractory linings, electrical insulators, dinnerware, dental implants, and high-temperature electronics.
What is grinding and milling?
Grinding and milling are two popular ceramic machining methods. They use separate tools and techniques to perform the machining tasks.
Milling machining uses a rotating cutter to cut and remove unnecessary material from a part to create specific shapes, slots, and holes. It is performed by various cutting tools from simple drills to complex CNC machines to manufacture molds and engine parts.
Grinding machining uses a grinding wheel to remove unwanted material from a part surface to produce a smooth surface and precise dimension. It is popular in precision engineering, toolmaking, and medical device manufacturing.
Conclusion: Ceramic machining is a critical technique in manufacturing ceramic components. It requires sophisticated tools and skilled personnel. It is the most expensive step in the overall production stages.
We hope the article provides a complete concept of ceramic product making and machining. We will return soon with more about ceramic milling machine and methods. Stay connected.