"Unlocking Productivity: Optimizing CNC Routing for Streamlined PCB Manufacturing"

Abstract: The conventional methods for forming PCB rigid boards - including CNC routing, mold stamping, v-cut, and beveling - each have their own strengths and limitations. This research paper zeroes in on a crucial step in the process: optimizing the rough routing tool path of CNC routing. By fine-tuning this critical stage, we demonstrate how manufacturers can drive significant improvements in efficiency and productivity, ultimately reducing overall production costs.

Through rigorous analysis and experimentation, this study provides valuable insights into maximizing the potential of CNC routing in PCB fabrication. The findings equip industry leaders with actionable strategies to streamline their operations and stay ahead of the competition.

Keywords: PCB fabrication; CNC routing; rough routing efficiency

1. Background

Computer numerical control (CNC)?routing is one of the most common methods for manufacturing PCB rigid boards. CNC routing is known for its high-quality board edges and significant cost advantages for samples and small batch orders. However, for large batch orders where customers specify CNC routing, the cost of expensive equipment and relatively lower routing efficiency can result in significant cost overheads.?Enhancing CNC routing efficiency without compromising product quality is one way to reduce production costs. The following sections delve into research on improving CNC routing efficiency and propose enhancement suggestions.

Factors Affecting CNC Routing Efficiency

Table 1 analyzes the factors influencing CNC routing efficiency from the perspective of 5M1E

Optimizing the routing program without increasing additional costs or compromising product quality implies an enhancement in routing efficiency. Relatively speaking, optimizing the routing program is a more effective method for improving CNC routing efficiency.

2 CNC Routing Program Optimization

2.1 Design Rules

Balancing quality and cost factors, a common rule in CNC routing is the combination of rough routing followed by fine routing. Rough routing removes excess material, while fine routing ensures that the formed edges meet dimensional and aesthetic requirements. Functionally, rough routing emphasizes cost efficiency, while fine routing focuses on quality.

Without compromising product quality, prioritizing rough routing as a starting point for cost improvement is preferred.

2.2 Rough Routing Efficiency

Significance of rough routing: Removing excess base material while leaving a certain distance for fine routing.

Rough routing time = Area of material that must be removed ÷ Rough routing tool efficiency. (※Special note: Rough routing distance × Tool diameter ≠ Material removal area)

?

Based on the above analysis, to reduce rough routing time, it is necessary to increase the efficiency of the rough routing tools and decrease the area of material that must be removed.

?

2.3 Analysis of Rough Routing Status

2.3.1 Rough Routing Path for Single Set Layout

In a single set layout, the rough routing tool travels counterclockwise around the set, leaving a distance of 0.05-0.15 mm. There is no wasted travel for the routing tool.

2.3.2 Rough Routing Path for 4-Set Layout

?

The rough routing path for a 4-set layout is created by duplicating the rough routing path of a single set layout. If the rough routing sequence for sets is 1-2-3-4, we can observe the following:

(1) During rough routing of set 1, the rough routing tool efficiency is close to 100%.

(2) During rough routing of set 2, the left side of set 2 is hanging, causing the rough routing tool to travel in empty space, leading to an efficiency of approximately 70% to 75%.

(3) Similarly, during rough routing of set 3, one side is hanging, resulting in an efficiency of around 75%.

(4) When rough routing set 4, both sides are hanging, resulting in an efficiency of approximately 50%.

Conclusion: If the rough routing path is created by duplicating layouts, there is wastage due to empty tool travel.

2.3.3 Rough Routing Path for 16-Set Layout

Following the analysis of the rough routing path for a 4-set layout, the wastage in the rough routing path for a 16-set layout becomes more severe. How much wastage is there? If the size of the PNL board is 540×620mm, with a layout spacing of 2.0mm, and using a 1.8mm rough routing tool with a travel speed of 13mm/second, then:

The distance wasted by the rough routing tool is approximately:

(520+600)×3=3360mm

The time wasted per board is approximately:

3360÷13=258 seconds=4 minutes 18 seconds

2.4 Resolving Rough Routing Wastage

Resolving the wastage in rough routing involves ensuring that the rough routing tool removes as much excess material as possible within the shortest travel distance, minimizing empty tool travel. Taking the examples of 4-set and 16-set layouts, the aim is to streamline the rough routing path, allowing the rough routing tool to avoid empty travel on each pass.

?

Optimized Rough Routing for 4-Set Layout:

Explanation of the optimized rough routing path for 4-set layout:

First pass:?Rough route the circular arc area in the middle of the layout.

※Note: If the radius of the circular arcs in the set is ≤5.0mm, the rough routing can be completed with fine routing without considering the arc area.

Second pass: Divide the PNL horizontally from left to right.

※Note: Similar to writing the Chinese character "田", start with a horizontal line in the middle, then complete the character with a vertical line.

Third pass: Make downward cuts from the top of the PNL, routing around the edges of the set.

※Note: If the radius of the circular arcs in the set is ≤5.0mm, straight lines can be used for rough routing, and the arc areas can be finished with fine routing directly.

After optimization:

(1) Except for the circular arc area in the center of the layout, the utilization of the rough routing paths is very high, with minimal empty travel and very high tool efficiency.

(2) The optimized 4-set rough routing requires only 2 to 3 tool lift operations. This saves 1 to 2 tool lift operations compared to the layout duplication method.

Optimized Rough Routing for 16-Set Layout:

After optimization:

(1) The utilization of the rough routing paths is very high, with minimal empty travel and very high tool efficiency.

(2) The optimized rough routing for 16 sets requires only 6 tool lift operations. This saves 10 tool lift operations compared to the layout duplication method.

2.5 Reducing the Area of Material that Must be Removed in Rough Routing

(1) Setting the Layout Spacing: For products requiring routing on PCB boards, a layout spacing of 1.8-2.0mm is recommended, using a 1.7-1.9mm rough routing tool.

(2) Manual Removal of Oversized Waste Blocks within Sets: Consider having the routing machine operator manually remove excessively large waste blocks within sets.

(3) Utilizing the Dust Extraction Port of the Routing Machine: The routing machine's dust extraction port should be capable of removing waste of a certain size. The waste within sets can be routed into smaller fragments that can be easily cleared away.

3. Effectiveness Estimation

Simulating based on a monthly delivery area of 100,000 square meters, approximately 350,000 panels would need to be produced. With an average of 6 sets per panel and a panel size of around 500×600mm, the routing machine operates with 6 axes, and the panels are stacked in sets of 3. With a layout spacing of 2.0mm and using a 1.8mm rough routing tool with a travel speed of 13mm/second, following the rough routing optimization in this document:?

Time saved per board operation = (480×2+580)÷13 + 3 tool lift times ≈ 120 seconds = 2 minutes

Number of machine operations needed with 6 axes = 350,000 ÷ 6 ÷ 3 ≈ 19,444 operations (this calculation assumes each board fills all 6 axes, but in reality, some boards may not, so the actual number of operations will be higher)

Monthly saving in machine count = 14,583 × 2 minutes ÷ 60 ÷ 24 ÷ 28 = 0.96 machines ≈ 1 machine

Conclusion: After rough routing optimization, for every 100,000 square meters of delivery area, the cost of one routing machine can be saved each month.

4. Implementation Recommendations

It is recommended to follow the 4M change process:

(1) The technical department, production department, and quality department should select representative models for trial.

(2) Record trial data for review and correction, considering factors such as product quality, production efficiency, operating procedures, inspection methods, risk assessment, and material loss.

(3) Import in small batches for review and correction.

(4) Update the formal SOP, provide training, and import in large batches.

(5) Evaluate whether old models need design updates based on actual circumstances.

(6) Summarize the results.

5. Horizontal Expansion/Extension

(1) To improve routing efficiency, reducing routing length, minimizing tool lift operations, reducing tool changeovers, and maximizing each routing operation's effectiveness are key. Following the rough routing and fine routing principles, fine routing paths can also be optimized further.

(2) Technical staff should be quality-conscious and cost-conscious. Improving routing efficiency is one of the evaluation criteria for skilled routing technicians.

(3) Within the industry, there are many routing subcontractors who need to make a profit. Learning cost reduction methods from these subcontractors can be beneficial.

Why Renchuangyi Electronic Co.Ltd (RCY PCB)?

One such industry leader is RCY PCB, a renowned PCB manufacturer that has pioneered innovative CNC routing techniques for 24 years. By implementing the optimization strategies outlined in this research, RCY PCB has achieved remarkable improvements in throughput and cost-effectiveness, delivering exceptional value to their customers. Our commitment to continuous improvement and technological advancement has solidified RCY PCB's position as a trusted partner for high-quality, efficient PCB manufacturing. We provide solutions that?are widely?used?in security,? industrial?control,?communication, medical?instrumentation, and?automotive electronics.?

For manufacturers seeking to unlock new levels of productivity in their PCB operations, the insights from this study, combined with the expertise of industry leaders like RCY PCB, provide a powerful pathway to success. By optimizing CNC routing and leveraging the latest advancements, companies can streamline their processes, reduce costs, and gain a competitive edge in the market."

Most?of?our?products?are?exported?to?the?United?States,?Europe,?Asia,?and?other?regionOur?factory?covers?an?area?of?over?48,000?square?meters,with?a monthly?production? capacity?of?over?120,000?square?meters.?Our?PCB?products?range?from?2?to?32?layers, including HDI,?High?Performance?Board,?Rigid-flex/Flex?Board?and?2L16L Multilayer? PCB’s,? FPC, RF,? Metal? Substrates.

Simply put : We?offer?"one stop?PCB?services"? to?meet?the? diverse needs ? of? our? customers.