Centralized Coolant Supply & Purification System Solution

Workshop Current Status

Types and quantity of machine tools: 50 CNC machines.

Reference for 3D drawing of the main unit of the centralized coolant supply and purification system

Centralized Coolant Supply & Purification System

The centralized supply and purification system is used for centralized coolant supply and return purification for multiple machine tools. The equipment adopts PLC automatic control, requiring no on-site manual attendance. It is equipped with functions including automatic coolant proportioning, intelligent start-stop, low-liquid-level alarm, quantitative proportioning, on-line monitoring of flow rate, concentration and PH value, data storage, centralized return purification, constant-pressure liquid supply and automatic water tank refilling. No manual intervention is needed, realizing an automatic management mode for coolant usage. Compared with the traditional manual proportioning, refilling and purification management, it greatly reduces labor costs, coolant consumption costs and waste liquid disposal costs, lowers tool wear, improves the surface finish of workpieces, and gives full play to the performance of coolant, thereby boosting processing efficiency and product quality. Application Scenarios: Workshops with a large number of CNC machine tools.

System Functions

Design Parameters

Coolant Type: Water-based cutting fluid
Maximum Processing Capacity of Purification Main Unit: 2.5m³/h
Filtration Precision: 10 microns
Oil Removal Rate: 98%
Bacteria Removal Rate: 96%
Voltage: 380V, Maximum Power of Main Unit: 12kW. The control power supply of each machine tool is connected to the machine tool electric box nearby.
Tap Water Flow Rate: Greater than 3m³/h
Number of Machine Tools: 50 CNC machines. According to the on-site layout of machine tools, 2 sets of vacuum return devices are required. Each return device controls about 25 machine tools, and coolant is centrally returned to the central main unit for purification treatment.
Each machine tool water tank undergoes return purification once every 20 hours; the liquid change time for each machine tool is 5–10 minutes.
Reuse Rate: 90% (subject to the impurity content of coolant used on site)
Footprint of Main Equipment Unit: Customized according to customer site conditions

Pipe Material: UPVC Pipe
Water Tank Liquid Change Method: The machine tool water tank pumps dirty fluid back via vacuum return. After dirty fluid pumping is completed, new fluid is immediately replenished to the water tank, automatically filling the liquid shortage during this process. If the machine tool needs to start up during liquid change, the constant-pressure liquid supply pipe directly supplies spray coolant to the machine tool. The liquid supply control power for a single machine tool is provided by that machine tool’s power supply. The customer shall cooperate to install liquid filling valves and sensors and connect the power supply.

Introduction to Return and Liquid Supply Pipeline Scheme

Pipelines are routed via overhead cable trays. The specific routing shall be installed according to the on-site layout, and can also refer to the layout of original machine tool cables and air pipelines.

Design Principle Diagram

Introduction to 3D Layout of Processing Main Unit

Design Principle Description: 

The vacuum negative pressure return mode features large flow rate and high flow velocity, eliminating the risk of chip accumulation inside pipelines. No return pump is required at the machine tool water tank, lowering the risk of pump damage caused by impurities. The pipeline circulates for self-cleaning, with regular flushing of return pipelines to prevent chip accumulation and inhibit microbial growth. The centrifugal purification device and precision filtration purification device, combined with the vacuum negative pressure filtration device, ensure that the whole system removes floating oil and solid impurities without generating other liquid waste, increasing the coolant reuse rate and reducing waste liquid output.

Advantages of Vacuum Return:

• After pumping, all liquid and impurities inside the pipe are emptied to prevent pipe odor and blockage.
• Vacuum return can pump out all liquid and impurities inside the water tank, featuring high return efficiency and better performance compared with water pump liquid delivery structures.
• During return, the liquid supply pipe connects to the machine tool water tank. Dynamic supply and return proceed automatically, realizing return filtration and liquid replenishment without shutting down the machine tool.

Vacuum Negative Pressure Return Flow Chart

Description of Supply & Return Pipelines and Return Devices

• Group machine tools according to on-site layout. Each zone is equipped with one return device and control cabinet. Coolant in machine tool water tanks is first pumped into the return device, and the return device then pumps coolant to the main unit for purification.
• No return pump is required at the machine tool water tank end; only return valves, liquid filling valves and liquid level control devices are needed. Meanwhile, the liquid supply pipe is split into two branches at the water tank end: one leads to the water tank, and the other merges into the machine tool liquid supply pipe. The supply valve leading to the water tank controls opening and closing according to the liquid level. Coolant for the machine tool is directly supplied to the water tank via the liquid supply pipe. The machine tool can keep running without affecting production, and connection to the customer’s machine tool spray pipeline is required.
• All coolant in the machine tool water tank will be pumped back to the main unit for purification. When the coolant in the tank is pumped to a set liquid level, liquid supply starts simultaneously to enter dynamic liquid change, and finally liquid is filled to the set liquid level in the water tank to complete liquid replacement.

Preprocessing Module

• Its main function is to filter coarse particles and floating oil visible to the naked eye.
• For filtering coarse particles, a stainless steel filter screen inclined structure plus automatic chip remover is adopted, which can quickly and effectively filter out particles and discharge them automatically, with a filtration precision of 0.5mm.
• The floating oil removal structure adopts our patented product — low-speed centrifugal cyclone structure, which rapidly removes more than 95% of floating oil on the coolant surface and discharges it automatically.

Sterilization and Deodorization Module

• Adopts nano aeration structure plus ozone.
• Ozone is a substance with extremely strong oxidizing property. It rapidly destroys microbial membrane structure through biochemical oxidation reaction. It is a broad-spectrum, high-efficiency and rapid bactericide that can quickly kill various microorganisms. With its oxidizing property, it can destroy the biological structure of bacteria, viruses and other microorganisms within a short time to deprive them of viability, and is effective against all the above strains.
• In metal working fluids, the main components causing odor and putrid smell are ammonia, hydrogen sulfide, methyl mercaptan, dimethyl sulfide, dimethyl disulfide, etc. Ozone can react with them chemically, oxidizing and decomposing them into non-toxic and odorless substances to achieve deodorization.

Deep Purification System Module

• Utilizing the inherent characteristics of substances and differences in impurity density ratios, multiple processes including centrifugation, micro-aeration and multi-layer baffles are combined. Heavy-phase substances sink rapidly while light-phase substances rise rapidly, so relatively clean liquid is obtained from the middle section.
• Mixed oil is automatically discharged by the oil-water separator, and solid particles are automatically discharged by the chip remover.
• The relatively clean liquid after separation undergoes precision filtration via filter paper tape to obtain highly purified liquid, while micro-impurities are conveyed and discharged by the filter paper tape.

Online Detection Module

• The online concentration meter can be installed on the external circulation pipeline of the blending liquid supply tank to realize online detection of the concentration of processing fluid, so as to control the surface quality and machining accuracy in the precision machining process.
• The instrument outputs a 4-20mA analog signal for remote control.
• If oil film adhesion occurs during blending, the newly developed automatic prism cleaning system can solve such problems.
• It is generally applicable to water-soluble cutting fluids, cleaning fluids, rust prevention fluids and other media. Accuracy: ±2.5%FS.

Product Diagram

Automatic Liquid Mixing Module

• The concentration is monitored in real time by the online concentration meter. When the concentration is low, the stock solution pump is started to supplement the stock solution, and the stirring motor is started at the same time for uniform stirring;
• When the concentration is high, the raw water valve is started to replenish water, and the stirring motor is started at the same time for uniform stirring;
• When the liquid level of the clean liquid tank is lower than the safe liquid level, the stock solution pump is started and the raw water valve is opened for proportioning according to a certain ratio, and the stirring motor is started for uniform stirring.

Constant Pressure Liquid Supply Module

• A variable frequency motor drives the water pump to inject cutting fluid into the liquid supply pipeline and maintain constant pressure; when the pressure of the liquid supply pipeline is lower than the set pressure, the water pump is started, and when the pressure of the liquid supply pipeline reaches the set high pressure, the water pump stops;
• The module is equipped with a flow stabilizing tank and a vacuum suppressor to effectively protect the stable operation of the constant pressure system. (Structural Diagram).

Topology Structure as shown in the figure:

• The machine tools are divided into several groups, and each group controls pumps and valves through ordinary cables for liquid adding and liquid return control.
• The machine tools in each group are controlled by touch screens, and the control system of each group communicates with the main host control system through the bus.
• The group control system is controlled by the main control system, receives instructions from the main control system, and uploads data to the main control system.
• The group control system is connected with the main control system through the bus, which reduces 90% of cable layout, reduces the failure rate and improves the reliability of the system.
• The communication medium adopts twisted pair cable, and the maximum communication distance can reach 10 kilometers, which meets the working conditions of large and scattered workshop space.
• The bus adopts a multi-master contention bus structure, which has the characteristics of multi-master station operation, distributed arbitration serial bus and broadcast communication.

Partial Control Pages of Centralized Liquid Supply Purification System

Control System of Centralized Liquid Supply Purification System

Benefit Analysis

Past Cooperation Cases of Similar Projects in Guangdong:

• 1 set of centralized liquid supply purification system for Wescatt Industrial (China) Co., Ltd.;
• 3 sets of centralized liquid supply systems for Wuyang-Honda Motorcycle (Guangzhou) Co., Ltd.;
• 1 set of semiconductor cutting fluid purification system for No.3 Factory of Dongguan Changying Precision Technology Co., Ltd.;
• 1 set of grinding wastewater purification system for No.3 Factory of Dongguan Changying Precision Technology Co., Ltd.;
• 1 set of cutting fluid purification system for Zigong Changying Precision Technology Co., Ltd.;
• 1 set of glass processing fluid purification and supply-return system for Dongguan Jinyuan Hardware Machinery Co., Ltd.;
• 1 set of centralized liquid supply system for Guangdong Wanhe Thermal Energy Technology Co., Ltd.

On-site Installation Requirements

Cutting Fluid Centralized Liquid Supply System Training and After-sales Service

(1) On-site installation and commissioning of equipment by the supplier
1. Procurement and installation of one set of centralized liquid supply system host and all accessories;
2. Installation of system power supply, air source pipeline, water pipeline and equipment;
3. Cooperate with the demander to carry out on-site liquid supply test;
4. Installation of liquid supply pipelines and liquid adding valves; and ensure that the pipelines can withstand a pressure of not less than 1mpa.
(2) Training and After-sales Service

1. Training 
1.1. Provide equipment training materials; 
1.2. Conduct operation training for production line employees; 
1.3. Conduct professional maintenance and simple repair training for equipment maintenance personnel.
2. After-sales Service 
1.1. The equipment enters the warranty period after acceptance, and the warranty period is 1 year; 
1.2. During the warranty period, respond within 24 hours after receiving the repair call; if on-site resolution is required, arrive at the site for maintenance within 48 hours; 
1.3. After the warranty period expires, apply for extended maintenance, and only charge labor and accessory fees.