Packagers clearly have mixed feelings about using PC-based controllers for their packaging machinery, if a recent Packaging World end-user survey is any indication. Nearly half of respondents report owning some PC-controlled packaging equipment (Chart 1). However, nearly 60% of those same respondents still specify programmable logic controllers (PLCs) when buying new packaging machinery. Only 20% specify PCs. (The rest either aren’t sure what their company usually specifies or leave the choice to the machinery builder.)
Like PW’s survey on packaging line networks (see PW, March ’00, p. 52 or packworld.com/go/networks), this survey of more than 80 respondents was conducted at PW’s booth at WestPack ’99 and Pack Expo Las Vegas ’99 last fall. It’s not a scientific sample, but it does document some of the thoughts and feelings that surround the issue of PC vs PLC control from the perspective of packaging machine end users. (For an intriguing look at how some prominent packaging machinery designers debate the issue, see our two-part series published last fall at packworld.com/go/pcctrl.)
Concerns and benefits
Survey respondents identified obstacles preventing them from adopting PC controls more wholeheartedly (Chart 2). The No. 1 concern, cited by more than one-third of respondents, was that of reliability. These respondents questioned whether a PC controller would freeze or crash the way desktop PCs occasionally do. Almost as many respondents were concerned that PCs would be difficult or time-consuming to learn how to program, indicating a comfort factor with PLC programming.
Finally, close to 30% of respondents simply didn’t perceive any benefit of using a PC rather than a PLC.
Those respondents who use PCs were asked to cite the benefit of PC controls. The leading answer was the ability for a single PC to perform both human-machine interface (HMI) functions and actual machine control. The next most important benefit, cited by more than one-fourth of the respondents answering the question, is that many PC controls are compatible with open networking protocols instead of being tied to a particular PLC maker’s I/O or network protocol. That usually translates into reduced controls acquisition and engineering costs because a greater number of suppliers typically support open standard vs proprietary ones. By definition, a proprietary standard is controlled by the company that devises that standard.
Nevertheless, growth ahead
Despite the caution with which packagers are approaching PC controls, more than half said that the number of such controls on their packaging lines has increased from two years ago. Even more respondents—about 63%—expect that number to further increase over the next two years (Chart 4).
And in one of the most astonishing findings of the survey, when asked point blank, three-quarters of respondents predict that PC controls will eventually become the dominant form of machine control for packaging, unseating PLCs (Chart 5). Yet more than half (60%) specify PLCs.
Of the respondents to the survey, conducted late last year, 54% worked for large companies (more than 500 employees), 28% worked for medium-sized companies (100 to 500 employees) and 18% worked for small companies (99 employees or fewer). About one-third worked in food or beverage manufacturing and 23% worked for pharmaceutical or medical device manufacturers. The remainder worked in a wide variety of other industries. Of the respondents who used PC controls, 40% used them for controlling a single machine; 36% used them for controlling an entire packaging line; and 24% used them for controlling multiple lines.
