CNC Machining and CNC Machine Tools, Technology of mechanical manufacture

Preparation of multi-species and small-batch production plans

Introduction: With the intensification of market competition, the market environment in which modern enterprises are located has undergone profound changes. Enterprise competition has increasingly emphasized competition based on customer needs. Therefore, the mode of production of enterprises gradually shifts to various advanced production modes based on flexible and automated production. At present, the types of production can be roughly divided into three types: a large number of running water production, a small variety of small quantities and a single production. At present, China’s manufacturing industry is mostly concentrated in small-batch production enterprises with a large variety of products. This mode of production has begun to occupy an increasingly important position. titanium machined parts

Multi-variety, low-volume production concept

Multi-species, small-batch production refers to the production of the specified period of production as the product of the type of object (size, type, size, shape, color, etc.) more, and each type of production less the number of production methods .

In general, this method of production is inefficient, costly and difficult to automate compared to mass production methods, and production planning and organization are complicated. However, under the conditions of a market economy, consumers’ preferences tend to be diversified, pursuing superior, unique and popular commodities that are different from others. As new products emerge in an endless stream, companies must adapt to this change in the market in order to increase market share. The diversification of enterprise products has become an inevitable trend. Of course, we should see the diversification of products, new products emerge in an endless stream, which will lead to some products that are not out of date, and the use value is still being eliminated. This is a great waste of social resources. This phenomenon should arouse people’s attention. titanium machined parts

Multi-species, small batch production features

1. Multi-category parallelism

Since many enterprises’ products are configured for customers, different products have different needs, and the resources of enterprises are exposed to more than one variety.

2 resource sharing

Each task in the production process requires resources, but the resources that can be used in the actual process are very limited. For example, the problem of device conflicts is often encountered in the production process, which is caused by the sharing of project resources. Therefore, limited resources must be properly deployed to meet project requirements.

3. Uncertainty of order results and production cycle

Due to the instability of customer needs, the unequivocal cycle of planned sets of nodes, people, machines, materials, laws, and rings, etc., the cycle of production is often uncertain. Projects with insufficient cycles need to occupy more resources , increasing the difficulty of production control. titanium machined parts

4. The changing demand for materials has led to serious procurement delays

Due to the order insertion or change of orders, external processing and procurement can hardly reflect the order delivery time. Supply risk is extremely high due to small batches and a single source of supply.

Difficulty in production of many varieties and small batches

1. Dynamic process path planning and deployment of virtual cell lines: emergency plug-in, device failure, and bottleneck drift.

2. Identification and Drift of Bottlenecks: Before Production and During Production

3. Multi-level bottleneck: assembly line bottleneck, the bottleneck of the virtual part of the line, how to coordinate the coupling.

4 buffer size: either backlog, or poor anti-interference. Production batches, transfer batches, etc. titanium machined parts

5. Production scheduling: We must not only consider the bottleneck, but also consider the impact of non-bottleneck resources.

The multi-variety, small-batch production model also encounters many problems in corporate practice, such as:
Multi-variety and low-volume production, mixed production is difficult
Unable to deliver on schedule, too much “firefighting” overtime
Orders need too much follow-up
Frequent changes in production priorities, the original plan can not be implemented
Increased inventory, but often lack critical materials
The production cycle is too long and the lead time is infinite expansion

Multi-variety, low-volume production and quality management

1. High scrap rate during commissioning

Due to the continuous change of products, we must constantly carry out product change and production commissioning work. During the change process, we need to modify the parameters of the equipment, change the tools and fixtures, compile or call CNC programs, etc. It will be wrong or missing. Sometimes the worker has just finished the previous product and has not yet fully grasped or remembered the relevant operation essentials for the newly replaced product, and is still “immersed” in the previous product operation method, thereby producing unqualified products and causing the product to be scrapped.

In fact, in the small batch production, most of the waste products are generated during the process of product change and debugging equipment. For multi-species and small-batch production, reducing scrapping during commissioning is particularly important. titanium machined parts

2. Post-examination quality control mode

The core issues of the quality management system are process control and total quality management.

In the company, the quality of the product is only a matter of the production workshop, the various departments are excluded, in the process control, although many companies have process rules, equipment operating procedures, safety regulations and job responsibilities, but due to poor operability and Too cumbersome, and with no monitoring means, the degree of its implementation is not high. For operations records, many companies did not conduct statistics, nor did they develop the habit of checking operation records every day. So, many of the original records are nothing more than a pile of waste paper.

Although many companies have passed the ISO9000 quality management system certification, they still implement the process of special inspection system, and stay at the stage of relying on quality inspection personnel to check, rather than looking for reasons from the process control and management. titanium machined parts

3. Difficulties in the implementation of statistical process control

Statistical Process Control (SPC) is a quality management technique that applies statistical techniques to evaluate and monitor all stages of a process to establish and maintain processes at acceptable and stable levels to ensure that the products and services meet the required requirements.

Statistical process control is an important method of quality control, and control chart is the key technology of statistical process control. However, traditional control charts are difficult to be applied to small-batch production because of their high-volume and rigid production environment.

Due to the small number of processed parts, the data collected can not meet the requirements of the traditional statistical methods, ie the control chart has not been made and the production has ended. Control charts do not play the necessary preventive role, losing the significance of using statistical methods to control quality. titanium machined parts

Quality Control Measures for Production of Many Varieties and Small Batches

In order to ensure the steady improvement of product quality under the conditions of small batch production under various varieties, it is necessary to establish detailed operation instructions and carry out the principle of “prevention first” and also introduce Advanced management concept, improve management level.

1. Establish detailed work instructions and standard operating procedures for the commissioning phase

The work instructions should include the required NC program, fixture number, detection method, and all parameters to be adjusted. Prepare work instructions in advance, you can fully consider various factors, through the preparation and proofreading, to gather the wisdom and experience of many people, improve the accuracy and feasibility. It can also effectively reduce online changeover time and increase the use of equipment.

The standard operating procedure (SOP) should determine each step of the commissioning work. Determine what to do and how to do each step in chronological order. Such as: the change of CNC machine tools, can be replaced by the claw – call the program – according to the program used by the knife number – check – knife – positioning the workpiece – set the zero – step-by-step execution of the program sequence will be a series of Scattered work is performed in a consistent order to avoid omissions. titanium machined parts

At the same time, for each step, how to operate, and how to make inspections also make provision. For example, how do you detect whether the jaws are eccentric after replacing the jaws? It can be seen that the debugging standard operation program is the optimization of the control point operation of the debugging work, so that each employee can do things according to the relevant provisions of the program, and there will be no big mistakes. Even if mistakes can be quickly detected through the SOP to identify problems and make improvements.

At the same time, since SOP itself is a product of continuous summarization, optimization and improvement in practical operation, a lot of people’s common wisdom has accumulated in this process. Therefore, SOP is comparatively optimized, has good enforceability, and can improve things s efficiency.

2. Really implement the principle of “prevention first”

We must change the theory of “prevention as the main, prevention as a combination of checks,” and “real-life” prevention. This does not mean that we will no longer be able to check, but will further check the functions, that is, the contents of the check. Including two aspects: First, the product quality checks, and then further process quality checks. To achieve 100% quality products, the first important thing is not the inspection of product quality, but the strict control of the production process in advance. titanium machined parts

Method for preparing multi-species and small-batch production plans

Comprehensive balance method

Comprehensive balance method is based on the objective law requirements, in order to achieve the planned goals, so that the relevant aspects of the planning period or the appropriate ratio between the indicators, interlinked, coordinated with each other, the use of balance sheet form, through repeated balance analysis and calculation to determine Plan indicators. From the perspective of system theory, it is to maintain the orderly and reasonable structure of the internal structure of the system. The comprehensive balance method is characterized by a comprehensive and iterative comprehensive balance between indicators and production conditions. It maintains a balance between tasks, resources and demand, between local and overall, between goals and the long-term. Suitable for preparing long-term production plans. It is conducive to tapping the potential of corporate people, finances, and goods.

2. Proportional method

The proportional method, also known as the indirect method, uses the long-term stable ratio between the two related economic indicators to calculate the relevant indicators for determining the plan period. It builds on the ratio between the relevant quantities and is therefore more affected by the accuracy of the ratio. Generally suitable for the accumulation of long-term data and information mature enterprises. titanium machined parts

3. The quota method

The quota method is based on the relevant technical and economic quotas to calculate the relevant indicators for determining the plan period. It is characterized by simple calculation and high accuracy. The disadvantage is affected by product technology, science and technology progress greater impact.

4. Network Law

Network law is based on the basic principles of network analysis technology to calculate and determine the relevant indicators. Its features are simple, easy to follow, arranged according to the order of operations, and can quickly determine the focus of the plan. The scope of application is very broad and it applies to all walks of life.

5. Rolling plan method

Rolling Planning Law is a dynamic method of planning, which is based on the implementation of the plan over a period of time, taking into account changes in environmental conditions inside and outside the organization to adjust the plan in due course and the corresponding plan to defer a period, the recent plan and long-term plan combined A method of planning.

Rolling plan method has the following characteristics:

The plan is divided into several implementation periods, of which the near-term plans are detailed and detailed, while the long-term plans are relatively crude;

After the implementation of the plan for a certain period of time, the content and related indicators of the subsequent plans will be revised, adjusted and supplemented according to the implementation and environmental changes;

Rolling plan method avoids the solidification of the plan, improves the adaptability of the plan and guides the actual work, and is a flexible and flexible production plan method;

The preparation principle of the rolling plan is “near fine and coarse”, and the mode of operation is “edge execution, side adjustment, and side scroll.” titanium machined parts

These characteristics show that the rolling plan method is constantly adjusted and revised along with changes in market demand, which coincides with multi-variety and small-batch production methods that adapt to changes in market demand. The use of rolling plan method to guide the production of multiple varieties and small batches not only improves the ability of enterprises to adapt to changes in market demand, but also maintains the stability and balance of the company’s own production. This is an optimal method. titanium machined parts

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