CNC, or computer numerical control machining, is a manufacturing process in which computer-controlled machines create precise and complex machine parts from various materials. Many businesses today rely on CNC machining for its accuracy in producing parts. But what about time?  

Typically, CNC machining is also great for quickly producing flawless,  high-quality parts. However, the delivery time is not constant for every scenario. It will vary based on some factors. 

That’s why we will explore the four key factors that tell you how long it takes to deliver CNC machined parts. So, if you are worried about your CNC machined parts not being delivered on time, go through this article completely. 

4 Main Factors to Affect Delivery Time of CNC Machined Parts

Understanding the factors that influence delivery times of CNC machined parts is crucial for effective project planning. The four key factors that dictate the delivery time of these parts include the complexity of the parts, materials used to create them, tolerance of the parts, and special cutting tools used in them. 

Let’s examine each factor in more detail to better understand how it impacts the delivery time.  

Complexity 

cnc machined part
CNC machined part

One of the primary factors influencing the delivery time of CNC machined parts is their complexity. These complexities can be categorized into several sections. For example, if you need to have thin walls or tight features, it can have a certain level of complexity. On the other hand, large workpiece sizes have their own level of complexity. Here’s how each of these complexities may impact the delivery time. 

Thin Walls and Tight Features 

Parts with thin walls or intricate features require more precise machining paths and potentially slower cutting speeds to avoid damaging the delicate aspects of the design. 

This translates to longer machining times compared to parts with simpler geometries. So, the more thin walls or tight features you need in your parts, the more time it will take for a company to deliver them. 

Number of Features 

Another crucial factor that increases a part’s complexity is its number of features. If a part has many features, such as holes, pockets, or slots, it will require more tool changes and programming time than simpler parts with fewer features. 

Each feature change requires the operator to stop the machine, swap the cutting tool, and restart the machining process. This process takes quite a significant amount of time and eventually increases the delivery time. 

Surface Finish Requirements

The desired surface finish of the machined part can also influence lead times. A smoother surface finish often requires additional machining passes with finer cutting tools, increasing the part’s complexity. 

On the other hand, a rougher finish might be achievable with a single pass using a more aggressive tool. It’s quite a straightforward process, which makes it less complex and time-consuming. So, if you are looking for a smoother surface finish, you will likely have an increased delivery time compared to a rougher finish. 

Workpiece Size

The workpiece size can also determine whether the parts are easy or hard to make. For instance, parts with unusually large sizes might not fit standard machine beds or require specialized handling during machining. It increases setup times and lowers machining speeds to ensure machine stability and safety. 

In contrast, creating smaller parts doesn’t require all that hassle, and they can be machined more efficiently within the workspace limitations of a CNC machine. That’s why working with smaller workpieces takes much less time than working with larger ones.

Multi-Axis Machining

Whenever you have to make more complex parts, you will need to use a multi-axis machining process, whether it’s 3-axis CNC machining, 5-axis CNC machining, or any other process. In these processes, the parts are manipulated along multiple axes during machining. 

This allows for machining intricate features from various angles but can add complexity to the toolpath programming and potentially extend lead times compared to simpler single-axis machining. 

Material 

cnc machined material
CNC machined material

The properties of the material chosen for the CNC machined parts play a significant role in determining delivery timelines. While some materials are easy to process and manipulate, some require additional processing time. Here’s a deeper look at how material selection can influence lead times:

Material Hardness

The first thing about materials that affect the timing of the CNC machining process is their hardness. Harder materials, such as certain alloys or tool steels, are more challenging to machine. They require slower cutting speeds and potentially specialized tooling to handle the increased wear and tear. 

As a result, harder materials require longer machining times than softer materials, which can be machined more quickly with standard tooling. For instance, machining a gear out of stainless steel will require slower speeds and more robust cutting tools than machining the same gear out of aluminium.

Material Brittleness

The next quality of material that impacts the processing time is its brittleness. Brittle materials are susceptible to cracking or chipping during the machining process. To prevent this, specialized techniques like slower cutting speeds, frequent tool changes, and customized tool geometries might be necessary. 

Taking these precautions often extends lead times compared to more solid materials that can be machined without worrying about any cracking or chipping. You can simply run the machine with regular settings and any extra care.

Heat Sensitivity

While it may not be a crucial aspect, a material’s sensitivity to heat can also dictate the CNC machining time. Some materials are sensitive to heat generated during the machining process. This heat can cause warping or distortion in the final part. To counteract this, specialized coolants or machining techniques might be required, adding to the overall lead time. 

A very popular scenario where you get to see this is, machining titanium as it requires specific coolants to prevent heat distortion. This impacts the machining process more than machining a less heat-sensitive material like aluminium.

Special Material Handling

Certain materials might require specific handling procedures during machining to prevent damage or warping. This handling can add up to the work or processes to even start machining the material. In these cases, it will increase the lead time significantly which translates to the delivery time as well. 

For example, some plastics might require specialized fixturing to maintain their shape during machining, adding an additional setup step that can extend lead times.

Material Availability: 

The readily available stock of the chosen material can also impact lead times. If the material requires special ordering or has limited availability, there might be additional lead time to acquire the necessary stock before commencing production.

Tolerance

cnc machining tolerance
CNC machining tolerance

Tolerance refers to the acceptable range of variation for a part’s dimension. It essentially defines the permissible deviation from the exact, specified measurement. It’s important to consider the different tolerance factors that impact the machining time. Such as –

Tighter Tolerances

Tighter tolerances demand a higher degree of precision in the final dimensions of the machined parts. Achieving these tighter tolerances requires more machining passes and meticulous toolpath programming to ensure each part meets the exact specifications. 

A great example would be a bearing housing that needs a shaft to fit perfectly. Such a tight tolerance on the housing diameter will require multiple machining passes with constant adjustments to ensure a precise fit. Afterwards, this translates to longer lead times compared to parts with looser tolerances.

Impact on Machining Process

Tolerance of the project also has an impact on the machining process which has an effect on the delivery time as well. Tighter tolerances can require slower cutting speeds to minimize material removal and maintain greater control over the final dimensions.

Additionally, more frequent tool inspections and measurements might be necessary to ensure everything is within the specified tolerance range during the machining process. These precautions contribute to increased machining times.

Balancing Needs vs. Time

Balancing the required precision and the desired lead time is crucial.  For some applications, looser tolerances might be acceptable, allowing for faster production times.  

A simple bracket might not require extremely tight tolerances on all dimensions, enabling faster machining than a high-precision gear component. Discussing your tolerance needs with the CNC machine shop during the initial design phase can help optimize precision and delivery timelines.

Special Cutting Tools

cnc machining tools
CNC machining tools

In some instances, a particular CNC machined part might require unique or specialized cutting tools that aren’t part of a machine shop’s standard inventory. These cases will require swapping the regular tools with the specialized ones, which usually consumes quite a lot of time. Here’s the impact specialized tools can have on time. 

Non-Standard Tooling Needs

If a part requires specific cutting tools that are not readily available, there might be additional lead time to acquire them before commencing production. This could involve custom-designed tools for intricate features or specialized tooling for challenging materials.  

A part with very small and deep internal channels might require a custom ball nose end mill with an extended reach to achieve the desired geometry. The lead time for designing, manufacturing, and acquiring these special tools will be added to the production timeline.

Impact on Machining Efficiency

Standard cutting tools are designed to efficiently machining common materials and geometries.  A non-standard tool might require slower cutting speeds or more frequent tool changes to achieve the desired results.  

While perfect for the specific feature, custom-designed tools might not offer the same optimized performance level as standard tools for that material. This can impact the overall machining efficiency and potentially extend lead times.

Programming and Testing: 

Implementing special cutting tools might require additional programming effort to ensure the toolpath is optimized for the specific tool geometry and capabilities. 

Additionally, the machine shop might need to perform test cuts to verify the effectiveness of the special tool before full production commences, potentially adding to the lead time.

Conclusion

After reviewing the factors, you can clearly see how these factors can determine how long it takes to deliver CNC machined parts. It’s very difficult to estimate a specific delivery time for these processes. Generally, lead times can range from a few days for simpler parts to several weeks for complex parts with tight tolerances and specialized requirements. 

Aside from all these practical factors, another factor that can greatly affect the delivery time is the CNC machining service you have chosen. If you go with service companies like Zintilon, you can expect a much quicker delivery than some other options. So make sure to consider this factor as well. 

FAQs

If you are still struggling to find answers to questions about the delivery time of CNC machined parts, here are some commonly asked questions we answered. 

How can I track the progress of my CNC machined parts order?

Reputable CNC machine shops typically offer order tracking systems or provide regular updates on the progress of your project. This might involve email updates, online portals, or designated contact points within the shop. Don’t hesitate to inquire about their tracking procedures when placing your order.

Are there cost differences associated with faster delivery times?

Generally, yes. Expedited services often come with an additional cost to prioritize your project ahead of others in the production queue. The exact cost increase will vary depending on the machine shop and the complexity of your project.

What happens if my CNC machined parts require special inspections?

Special inspections, such as dimensional checks or material verification, can add to the delivery timeline. However, these inspections ensure the parts meet the required specifications and quality standards. Discuss your inspection requirements with the machine shop beforehand to factor in the additional time needed.

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