How to Select an Automatic Pick-and-Place Machine


Reading time ( words)

This is the third in a series of articles designed to help buyers analyze and select SMT equipment for PCB assembly, and examines automatic pick-and-place machines, the most complex component in a circuit assembly operation. Because of this complexity, the next few columns will address different functions in this process.

Automatic pick-and-place machines are much more common than manual or semiautomatic machines, but they also have the greatest range of capabilities and cost. This column will focus on features and capabilities and include some cautions regarding reliability of low-cost machines, including:

• Production volume ranges (CPH)

• Accuracy and repeatability specs

• Pick-up and centering methods

In future columns, I will address size, machine accuracy, encoders, feeders and mechanical positioning methods.

When starting your evaluation process, there are two defining factors to keep in mind, which determine what category fits your machine needs. The No. 1 principal factor is components per hour (CPH), and the secondary factor is machine capability.

Production Volume

As in the previous column, it’s constructive to start by addressing production ranges for various types of machines, since this is the No. 1 factor in your evaluation process. For purposes of comparison, since all circuit boards vary in size and complexity, we talk about volumes in terms of components per hour, or CPH. The following table offers a general guideline of machine categories defined by their CPH.

Machine Capabilities

This is the second defining factor in helping choose the correct auto pick-and-place machine for your needs. Here, we will only be talking about two aspects of machine capability: accuracy and repeatability, and pick-and-place centering methods.

Accuracy and Repeatability

For production machines, we typically recommend looking for a machine with accuracy of +/- .0001” and down to fine pitch capability of 12 mil on a repeated basis. Less expensive machines often don’t meet this spec. Most low-cost machines will also not come standard with a computer or software which could help with the repeatability aspects if not the accuracy. While some may offer enhanced technology, most do not.

Pick-and-place Centering Methods

There are four methods for pick-up and placement:

1. No centering mechanism

2. Mechanical (jaws)

3. Laser centering

4. Vision centering

Method 1: No centering mechanism other than relying on the component’s pick-up point for placement. In other words, the part is not physically centered after being picked up by the tool head, and if it’s picked off-center on the tool, it will be off-center when placed on the board. Obviously, this is not a very accurate placement method because there is no definable tolerance. You can expect to find this method used by hobbyists or instructors, but certainly not in any type of precision production environment. There are not many options available either, and long-term reliability is questionable.

• Pros: Low cost

• Cons: Low accuracy, repeatability and long-term reliability, no options, or spare parts

• Size range: No definable tolerances

Read The Full Article Here

Editor's Note: This article originally appeared in the March issue of SMT Magazine.

Share

Print


Suggested Items

Maximising Performance and Reliability of Automotive Electronics With Conformal Coatings

11/20/2019 | Phil Kinner, Electrolube
While the value of the electronic systems in a modern vehicle typically exceeds 20% of the total vehicle cost, many estimate that this value will exceed 35% within the next five years. With the increased adoption of electronic vehicles and the development of the internet of things (IoT)—which has brought us driverless cars like those being tested by Google in California and BMW on the roads of Bavaria—the future of this industry is starkly different from that of the 1970s when electronic fuel injection systems were first introduced to mainstream production.

Solder Mask Evolves into a Truly Additive Process

09/09/2019 | John Fix, Taiyo America Inc.
The 5G era is creating quite a bit of work for many PCB engineers as the materials required to keep up with the speed, frequency, and latency requirements need to be defined and qualified. Solder mask, for example, now becomes a truly additive process. Read on to find out how and why.

PCB Design Training: More Critical Than Ever

09/05/2019 | Andy Shaughnessy, Design007 Magazine
I interviewed Gary Ferrari of FTG at the IPC High-Reliability Forum and Microvia Summit in Baltimore. Gary is a co-founder of the IPC Designers Council and a longtime advocate for PCB design and PCB designers. We discussed the crucial role that PCB designers play in the entire electronics development process, and how IPC and the Designers Council are helping to educate and inform the next generation of designers.



Copyright © 2020 I-Connect007. All rights reserved.