What is a Dust-free Workshop?
Design requirements for a 10K class dust-free injection workshop
A dust-free workshop refers to the removal of particulates, harmful air, bacteria and any other pollutant in the air within a set-out space. This also includes the indoor temperature, cleanliness, indoor pressure, air velocity & distribution, noise, vibration, lighting, and static electricity. These are all the factors that need to be monitored and controlled within a certain range of requirements in order to be classified as a dust-free workshop. These workshops can also be referred to as clean workshops, cleanrooms or dust-free rooms. The purification of a workshop can be divided into several categories based on the degree of purification and regional environment.
What are the grades of a dust-free workshop?
For many industries, it is a necessity to build dust-free workshops. However, every industry has different products that have varying requirements for purification levels of a dust-free workshop. Even within the same industry for varying production environments, different clean workshops have different production tasks. Therefore, the purification level needs to be set up according to the situation itself. For example, the cleanliness levels of the production room, packaging room, and laboratory are not the same. It is impossible for them to all be at 100 level, 10,000 level, or 100,000 level purification. We have to consider not only the purification level requirements but also the cost requirements.
Air cleanliness class: the classification standard is based on the maximum concentration of particles being greater than or equal to the particle size in the unit volume of air in a clean space. In China, dust-free workshops are tested and accepted according to the empty state, static state, and dynamic state condition, in compliance with “GB50073-2013 Clean Workshop Design Specification” and “GB50591-2010 Clean Room Construction and Acceptance Specification”.
The cleanliness and continuous stability of pollution control are the main standards for testing the quality of dust-free workshops. The standard is separated into several levels based on factors such as the regional environment and cleanliness. For this, the international standard and domestic regional industry standards can be used to measure it.
The classification standards of a clean workshop can be defined as the following:
The expected standard of a 10K class dust-free workshop includes:
- The maximum allowable number of dust particles (per cubic meter) is equal to or less than 2,500
- The number of particles larger than or equal to 0.5 microns shall not exceed 350,000, and the number of particles larger or equal to 5 microns shall not exceed 2,000
- The maximum number of microorganisms such as planktonic bacteria shall not exceed 100 per cubic meter; the number of bacteria shall not exceed 3 per petri dish.
- Pressure difference: the pressure difference of clean rooms with the same cleanliness levels should be the same. The pressure difference between adjacent clean rooms of varied cleanliness should be equal to or more than 5Pa. The pressure between clean and non-clean rooms should be equal to or more than 10Pa.
When there are no special requirements for the temperature and humidity in the 10k class dust-free workshop, it is advisable to wear clean work clothes. The temperature is generally controlled at 20-22℃ in winter, rising to 26-26℃ in the summer with a fluctuation of ±2℃. The humidity of the cleanroom in winter is controlled at 30-50%, and in the summer months, it is controlled at 50-70%.
- Power distribution: the general illuminance value of the main production room in the clean area should be more or equal to 300Lx. The illuminance value of the auxiliary studio, airlock rooms, corridors, personnel purification and material purification rooms should be 200-300Lx.
- Noise control: during dynamic testing, the noise level in a 10K class cleanroom should not exceed 70 dBA. During static testing, the noise level of the 10K grade turbulent-flow clean room should not be greater than 60 dBA.
Immetech has a 10K class dust-free injection molding workshop and assembly workshop. The scrap, feeding, and mixing workshops are completely separated to prevent the mutual influence between the different production links. The feeding and mixing rooms are separated into small rooms, and the scrap room is far away from the dust-free workshop area. The mold room is placed outside the dust-free injection workshop. Before entering the dust-free room, it must be air-showered first. Also, the mold hoisting adopts a small gantry electric hoist.
Furthermore, dust-free air-conditioning boxes are installed to make the air purification and filtration system meet the design requirements for a 10k standard room. Large amounts of hot exhaust gas can be generated during the injection molding process, and this is collected and discharged out of the cleanroom. Activated carbon exhaust treatment equipment is installed to centrally treat and discharge the exhaust gas.
Fully automatic feeding, picking and conveying systems are in place. A high-pressure automated feeding system is used for raw injection molding materials, through stainless steel pipes. The injection molding machine picks up parts using a fully automatic robotic arm combined with a ramp conveyor beltline for picking up parts.
The operators work in the packing & checking room, and the conveyor belt transports the products to a large beltline. The finished products are transported to the inspection room through the large beltline, where the operators assess, classify, and arrange the qualified products.
How to look after the workshop and maintain it to a 10k class standard
This is achieved by:
- Keeping the cleanroom floor, wall, ceiling, injection molding machine body, and conveyor line, clean and spotless.
- Replacing the air filter in the clean air-conditioning box and the high-efficiency filter every six months.
- Cleaning up all pollution sources such as oil stains after changing the mold.
- All items and personnel entering and leaving the cleanroom for injection molding passing through the air shower room and cargo shower room.
- Employees being trained in accordance with the dust-free requirements. Any personnel entering the 10K class dust-free workshop must follow the purification procedure, wear masks & protective clothing, wash & disinfect their hands, and dress in compliance with the rules.
This is how the air purification and exhaust process of injection molding works in a 10K class dust-free workshop:
Outdoor air → filter → central air conditioning heating or cooling → high-pressure fan → air supply duct → high-efficiency air supply outlet → cleanroom → exhaust gas collection bell mouth → exhaust duct → activated carbon waste gas treatment equipment → high-pressure exhaust fan → discharge at an altitude of 15 meters.
The 10K class dust-free workshops change air 25-30 time per hour, with the air purification time not exceeding 30 minutes after the completed air change. This is because the injection workshops need to eliminate particles, harmful air, bacteria and other pollutants in the air within a certain space. There is also control of the indoor temperature, cleanliness, pressure, air velocity & distribution, noise, vibration, lighting, and static electricity within the scope of requirements for a 10K class level cleanroom.
Should your project require dust-free workshops at a 10k class standard get in touch with one of our team via the following:
Email: [email protected]
Address: Immetech Industrial Co. Ltd., Building F, Huixin Industrial Park, Daxing Rd, Yangwu, Dalingshan Town, Dongguan City, Guangdong, China 523839