Even small-batch prototypes can be used to verify precision machining techniques! Main processing methods and ordering tips.

Processing technology

With the advancement of design tools such as CAD and CAE, prototype-less design verification is becoming widespread. However, for parts where functional accuracy directly impacts product performance, such as rotating mechanisms and positioning mechanisms, the process of creating and verifying prototypes remains crucial.

Especially for precision parts such as shafts and lead screws, geometric accuracy such as roundness, cylindricity, and surface roughness, in addition to dimensional tolerances, greatly affects their function.

Therefore, prototyping using precision machining is essential to confirm whether the performance envisioned during the design phase can be reproduced with the actual parts.

This article explains why precision machining is necessary even for small-batch prototypes, key points to consider in machining design during the prototyping stage, and the process for ordering precision parts.

~Regarding the prototype of Sanwa needle bearings~

We don't just accept processing contracts.
Becoming a "development partner" for precision machining, supporting you from concept to mass production.

Prototyping and small-batch manufacturing in new product development are crucial. During the design and development phase, it's essential to overcome the "mass production barrier" and meet stringent functional requirements within limited deadlines and budgets.

Our company is not just a "prototype maker" that simply takes drawings and processes the parts.
Our greatest strength is our support system that involves us from the very beginning, including our clients' initial concepts, planning, and development.

Proactive solutions to mass production risks	In-house development of specialized equipment	We support you throughout the entire product lifecycle.

We identify problems from the prototyping stage and propose improvements such as enhanced machinability and cost reduction.	We can handle everything from developing and building specialized equipment that is more cost-effective and ensures consistent quality, with a view to mass production.	We provide total support from planning to product end-of-life, including the individual production of precision jigs for molds and manufacturing equipment.

We are committed to providing full support as your partner in resolving all kinds of problems in your development environment, including highly demanding precision machining that other companies may find difficult to handle.

【Related article】
Prototype production possible from as little as one piece

table of contents

Three approaches to "small-lot prototyping" with mass production in mind.
Main types of parts that require precision machining during the prototyping stage
The process for prototyping precision machined parts
Frequently Asked Questions about Prototyping and Small-Batch Manufacturing in Precision Machining
Summary | For critical parts, even small-batch prototypes should be considered with precision machining in mind.

Three approaches to "small-lot prototyping" with mass production in mind.

In the prototyping stage of product development, it's not uncommon for processing to be done simply to confirm the shape.

However, if preliminary processing is carried out under conditions different from those used in mass production, serious problems such as "insufficient precision" or "cost-incompatible" will arise when mass production begins. Truly valuable prototyping lies in eliminating potential problems that may occur during mass production in advance.

Here, we will outline "three key concepts" for precision machining in small-batch prototyping, ensuring that the process goes beyond simple machining.

The role and purpose of prototyping
Different processing design approaches for small-batch prototyping and mass production.
Setting tolerances and heat treatment conditions that can be handled in prototyping.

1. Clarifying the role and purpose of prototyping.

Prototypes are created not only to confirm the shape, but also to verify that the designed parts perform the intended functions and performance.The key advantage of conducting operational and assembly verification tests under actual usage conditions is that design problems can be identified before mass production.

For example, in the case of rotating mechanism parts, even if the dimensions on the drawing are correct, geometric accuracy such as roundness, coaxiality, and surface roughness can affect the actual rotation, causing runout and friction.

Therefore, when the machining accuracy of a component directly impacts its functional performance, it is crucial to conduct verification through precision machining, even at the prototype stage, with mass production in mind.

Furthermore, the key to success lies in clearly defining the purpose of each prototype: either deliberately setting a high level of precision to check for room for performance improvement before proceeding with detailed design, or conversely, checking whether the function can be maintained even with a lower level of precision to find clues for cost reduction.

2. Different approaches to processing design for small-batch prototyping and mass production.

In small-batch prototyping, processing is performed for the purpose of functional verification, but in mass production, the process design becomes crucial in terms of "how to produce parts of the same quality cheaply and consistently." The main differences are as follows:

Comparison item	Trial production	Mass production
Objective	- Verify that it functions as designed.	- To consistently produce parts of the same quality.
How to think about accuracy	Sometimes, precision is only applied to the necessary parts. - Accuracy verification may be performed under different tolerance conditions as needed.	• Design tolerances to match process capability. Reproducibility and stability are important.
Processing method	We can flexibly handle single-piece processing and special setups.	Processing that takes into account processing time, cost, and process efficiency.

A processing method that works well in prototyping may not necessarily work in mass production.That's why, from the prototyping stage, we propose drawings (VA/VE proposals) that take into account processing efficiency and costs during mass production.

3. Setting tolerances and heat treatment conditions that can be handled in prototyping.

In the prototyping stage, drawing tolerances and heat treatment conditions are often not fully determined.However, with precision parts, tolerance settings and heat treatment conditions greatly affect the manufacturing method, so it is necessary to set certain conditions even at the prototyping stage.

Clearly defining "to what extent to reproduce the precision and process of the final product" during the prototyping stage will lead to stable quality during mass production.

For example, in the mass production of shaft parts, it is common practice to perform grinding to account for distortion after heat treatment. In this case, even at the prototype stage, it is necessary to consider the processing steps that take into account dimensional changes after heat treatment.

Furthermore, if the requirements for roundness and surface roughness are stringent, verification may need to include not only cutting processes but also finishing processes such as grinding and lapping.

At our company, we engage in close consultations with our clients from the very beginning of the design process, when there are many uncertain elements.We support smooth development without rework by providing advice on appropriate heat treatment conditions and realistic tolerance settings.

Main types of parts that require precision machining during the prototyping stage

Why is extreme precision machining required during the prototyping and small-batch production stages?

This is because not only is accuracy in size (dimensional tolerance) important, but also "geometric tolerances" such as roundness and parallelism, as well as "surface roughness" measured in microns, directly impact the performance and lifespan of the final product.

To prevent major rework caused by defects being discovered after mass production has begun, we will explain four typical component groups that require particularly rigorous precision verification during the prototyping stage.

Rotating mechanism components (shafts, rollers, etc.)
Positioning mechanism components (lead screws, sliding screws, etc.)
Sliding parts and mating parts
Micro and small-diameter precision parts

Rotating mechanism components (shafts, rollers, etc.)

In rotating mechanism components such as motor shafts and conveyor rollers,Geometric precision, such as roundness (how perfectly round it is), cylindricity, and coaxiality (whether the axis is centered), directly affects rotational performance.

In particular, in components around high-speed rotating motors and bearings, even a runout or distortion of just a few microns can cause significant vibration (chatter), abnormal noise, and premature wear.

Key points for prototyping and small-batch processing
Even slight distortions in rotating mechanism components such as shafts and rollers can lead to critical malfunctions.

Therefore, it is essential to achieve extremely high roundness and a smooth surface finish not only through lathe machining but also by using even more precise "centerless grinding" processes, and to test and verify the actual rotational conditions and durability.

Positioning mechanism components (lead screws, sliding screws, etc.)

In positioning mechanism components used inside semiconductor manufacturing equipment, medical devices, optical instruments, etc.,Precise movement (feed accuracy) down to the micron level is required.

Even if the dimensional accuracy is perfect, if the screw pitch accuracy or surface smoothness is insufficient, "backlash" (looseness due to gaps in the machine) will occur, making accurate positioning impossible.

Key points for prototyping and small-batch processing
It is crucial to use the same materials and high-precision machining as the final product from the prototyping stage, rigorously checking the actual feed accuracy, friction characteristics, and presence or absence of play, and then feeding this information back into the design.

What is a slide screw? An easy-to-understand explanation of its types, uses, and the difference between it and a ball screw

Sliding parts and mating parts

These are parts that move by rubbing against each other, such as pistons and cylinders, bushings and sleeves, as well as parts that fit together tightly without any gaps, known as "sliding parts."

If the clearance (gap) or surface roughness of these parts is not set correctly, they can become stiff, or seize or gall due to frictional heat, leading to instant failure.

Key points for prototyping and small-batch processing
The key to successful mass production lies not only in calculations based on drawings, but also in "fine-tuning" between actual small-batch prototypes to optimize tolerances (clearances).

Micro- and small-diameter precision parts (micro-components, small-hole nozzles, etc.)

These are microscopic, small-diameter components that are difficult to see with the naked eye, such as the tip components of medical catheters, extremely small sensor parts, and thin pins.

Thin and long parts (with a large L/D ratio: length to outer diameter) are directly affected by "deflection" (relief) caused by the pressure of the cutting tool during machining, as well as slight tool wear, making it extremely difficult to achieve the specified precision.

Key points for prototyping and small-batch processing
With mass production in mind, establishing the optimal processing methods (manufacturing techniques) during the prototyping stage, such as "how to support the material" and "in what order to cut to prevent warping," helps prevent a decrease in yield (percentage of good products) during mass production.

The process for prototyping precision machined parts

In prototyping precision parts, it's crucial not only to machine them according to the drawings, but also to consider the design intent and operating conditions when planning the machining process.

Especially for components related to rotational and positioning mechanisms, the final accuracy and function can vary greatly depending on the manufacturing method and process design. Therefore, it is desirable to proceed in collaboration with the manufacturing company from the prototyping stage.

This section outlines the process for prototyping precision machined parts.

meeting
making the plan
Order
Product processing, inspection, and delivery.
Evaluation

1. Meeting

In the initial stages of prototyping, we organize the intended use of the parts, required performance, and anticipated operating environment, and share this information with the processing manufacturer.

Especially with precision parts, drawings alone can sometimes fail to convey which geometric tolerances are particularly important. Therefore, when considering mass production, it is crucial to consider the mass production process from the prototyping stage.

By sharing information about the application and structure of the parts, such as whether they are rotating parts, positioning mechanisms, or sliding parts, it becomes possible to consider appropriate processing methods and process designs.

2. Drawing creation

In prototype manufacturing, the completeness of the design drawings greatly affects the quality of the manufacturing process.By clearly specifying not only dimensional tolerances and material requirements, but also geometric tolerances and surface roughness as needed, the machining process can be made more concrete.

However, in many cases, the design is not fully finalized during the prototyping stage. Even in such cases, by prioritizing the setting of tolerances and precision conditions for functionally important parts, it is possible to manufacture the parts necessary for actual functional verification.

3. Order

We organize the drawings and specifications and then place the order.For precision parts, the processing method varies depending on the material, heat treatment conditions, and finishing processes, so it is important to confirm the processing range, delivery time, and cost in advance.

Especially in small-batch prototyping, individual part processing and special setups may be required, resulting in a different cost structure compared to mass production. Therefore, clearly stating the purpose of the prototype and the mass production plan when making a request will make it easier to determine the appropriate processing method.

4. Product processing, inspection, and delivery

In the manufacturing process, precision is ensured by combining cutting processes such as turning and milling with grinding and heat treatment.Finished products are delivered after undergoing dimensional inspections and geometric accuracy measurements.

In addition, for rotating and mating parts, accuracy checks may be performed to simulate the rotational performance and mating condition during assembly.

5. Evaluation

The delivered prototype parts will be incorporated into the actual equipment and mechanisms for evaluation.Here, we check the operational performance, durability, and ease of assembly, and consider whether there are any areas for improvement in the design or manufacturing conditions.

Based on the results of prototype evaluation, it is common practice to revise drawing tolerances, change manufacturing methods, and reflect these changes in the mass production design. Through such verification, it becomes possible to establish a stable mass production process.

Frequently Asked Questions about Prototyping and Small-Batch Manufacturing in Precision Machining

In precision machining prototyping and small-batch production, many questions arise regarding cost, accuracy, design conditions, and other factors.

Here, we'll introduce some frequently asked questions from designers and developers.

Q1. Will the unit price be higher for precision machining in small batches or prototypes?
Q2. What are some points to keep in mind when transitioning from prototyping to mass production of precision machining?
Q3. Is it possible to consult about precision machining even if the drawings are not yet finalized during the prototyping stage?

Q1. Will the unit price be higher for precision machining in small batches or prototypes?

Regardless of the production volume, initial processes such as machining setup and jig preparation incur a certain cost.Therefore, the smaller the quantity, the larger the proportion of the cost per unit, and small-batch prototype processing tends to have a higher unit price compared to mass-produced items.

Q2. What are some points to keep in mind when transitioning from prototyping to mass production of precision machining?

Even if a product can be manufactured as a single prototype, it doesn't necessarily mean that the same consistent quality can be achieved in mass production.Therefore, when transitioning to mass production, process design that takes into account process stability and optimization of processing time is required.

Since the order of processes such as heat treatment and grinding can affect dimensions and precision, it is important to consider process design with mass production in mind from the prototyping stage.

Q3. Is it possible to consult about precision machining even if the drawings are not yet finalized during the prototyping stage?

Many processing manufacturers offer consultation services even when the design is still in progress.By considering processing methods and tolerance settings from an early stage, it is possible to develop processing specifications that aim for stable production.

It is important to consider prototyping from both a design and manufacturing perspective, as it can lead to suggestions for appropriate tolerance settings based on the required functional precision, as well as proposals for shapes that are easy to manufacture.

Summary | For critical parts, even small-batch prototypes should be considered with precision machining in mind.

In prototyping, it is crucial to verify the machining accuracy and process conditions that will meet the actual functionality requirements.Especially in precision parts such as rotating mechanisms and mating components, geometric accuracy, including roundness and surface roughness, in addition to dimensional tolerances, greatly affects performance.

In the development of precision parts, verifying machining accuracy from the prototyping stage is crucial for ensuring stable quality during mass production. Even when machining small batches of prototypes, designing the process and considering machining conditions with mass production in mind, including setup and jig preparation, from the prototyping stage will help stabilize quality and prevent problems during the transition to mass production.

Sanwa Needle Bearings can handle prototype machining of small diameter shafts and precision parts, starting from just one unit.We also handle machining consultations and process planning from the design stage, so please feel free to contact us if you are considering small-lot prototyping of precision parts.

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