[ Return ]

More pros fewer cons

New Zealand Forest Industries, October 2001

Last month's article on scanning and optimising, Scanning the Pros and Cons, prompted Mike Howie of Southern Cross Engineering to point out some of the more significant gains that can be made with this technology.

He says calculating the return on scanner and optimising investment is possible even when other improvements incorporating significant mechanical changes have been made.

"Scanners will always increase recovery on a carriage. Most people going for a full tapering carriage with fully independent knees are going to get a 3% increase in recovery straight away. A photo eye scanner will add a further 4% on top of that. If you add a 3-D scanner that's 10%, so you're looking at a 7% minimum improvement in recovery. With a scanner on the trimmer, you can achieve 7% - 10% on the edger, 15% minimum on random widths. This order of improvement is well documented in the USA on over 600 sites. It's worth noting a good proportion of headrig scanners have gone into hardwood milss where, if anything, the increases are even greater. The structure of the logs is the same - knotty low grade cores and grade timber around the outside.

"Any decent scanner is faster and more consistent than a person. If mills are overriding their optimisers, we as suppliers should do more to train people properly, particularly in the area of calibration.

"One of the biggest things in the whole optimiser debate is that any 3rd Form maths student can draw a circle then calculate how far you have to go in to get the opening face. It's not the maths (that are the challenge) it's collecting accurate enough data, fast enough, about every single log. Compared to humans, optimisers are always consistent.

"You have to analyse your ROI from a log cost reduction point of view. If you treat it as "free wood" it skews your returns and recovery rate, because there's still the cost of handling, kiln drying, processing and wrapping. The only thing that's "free" is the resource. It's not a perfect calculation but the simplest way is to say this is an X% reduction in log costs and work that out over a year.

"For so many years sawmills didn't understand the technology. Now there's a PC on every desk and the general understanding about how these things work is much greater. As suppliers we need to be able to answer quite detailed questions about things like operating systems - and justify the answers. We can't just go to someone and say you'll get 7% improvement in recovery, we have to explain why and what justifies a good control system. We support it and know what it takes to make it perform properly. "The main thing is to get the supplier involved. There's nothing wrong with using a consultant but they've got to be knowledgeable (or admit when they're not!) and understand what the mill's trying to do."

The "shopping list" approach is often a cause of problems says Howie. "We prefer people to tell us where they are and where they want to be - here's the kind of logs we want to buy, here's the type of product and market I'm looking at, tell me what to put in the gap."

He adds it's important to remember that with edger optimisers it's not about going fast, it's about recovery.

"How many mills in New Zealand need to do 50 boards a minute?" he asks. "Most would be happy to do 20."

[ Return ]