Conveyor Blog

Having good partners to work with on projects makes life easier. Econocorp is a great example. They’re based in Randolph, MA and make great cartoners and case packers. We’ve begun working on more and more projects with them, recently handling tapered candles and and cartons of chocolate. What does it take to forge a partnership? I think it’s trust and openness.

I’ve known their VP Mark Jacobson my entire life and some of his accomplishments include being a past chairman of PMMI being inducted into the Packaging Hall of Fame in 2009. His partner, Wayne Goldberg, has given me tons of of advice about manufacturing and project management. Any time I have talked to these guys they have opened up their business to me far outside of the current project. Inevitably, disagreements come up during the project concerning who is responsible for what and I think the openness about each other’s businesses help us quickly resolve scope issues.

Here’s a video of our Taper Flo handling tapered candles. I played the part of “robotic pick and place.”

Update: As of 2/15/2011 we are no longer actively looking for new candidates. Thanks!

The Project Engineer is the best position in our company, because you are responsible for everything from idea to startup. Can you coordinate the efforts of all departments to make sure the equipment is designed, fabricated, assembled, and shipped properly? Can you effectively communicate with all types of customers from factory engineers, to maintenance mechanics, to vice presidents, and line operators? Are you looking for an opportunity to travel the world?

We’re looking for an engineer who isn’t afraid of responsibility, can think creatively, and loves machines. Not literally loves machines, that’s frowned upon here, but someone whose personal identity and satisfaction is tied to their ability to Make Things Work. We’re also looking for someone who is a life long learner and keeps up to date on new technology and manufacturing processes.

You will be working with a group of fantastic 3D designers to implement your design choices, but you must also have strong 3D modeling skills yourself. Solidworks experience is strongly preferred, but please apply if you’ve used similar packages.

If you want to apply for this position, email me your resume today.

Below is our official description of this job.

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PROJECT ENGINEER

EDUCATION/EXPERIENCE REQUIRMENT:

o Bachelor of Science in Engineering (Mechanical preferred).
o Minimum of 2+ years experience in an engineering function. Supplier/vendor interaction and/or customer interface experience a definite plus.
o Solidworks (or equivalent 3D modeling) experience required.
o Ability to organize and prioritize multiple tasks.

JOB DESCRIPTION:

o Under the general supervision of the Engineering Manager, plans and oversees the coordination of all technical aspects of the projects assigned. Projects assigned are based on schedule and project size.
o Responsible for the interface with the Sales Department to determine that all project requirements and customer expectations are met.
o Responsible for project compliance with all applicable codes and customer supplied specifications.
o Responsible for the development of conceptual designs that are passed along the design staff for formal design and detailing.
o Conducts testing of the finished product and final inspections prior to shipment to customer.
o Generates specifications for and evaluates bids from outside vendors/suppliers.
o Supplies the Engineering Manager with daily schedule updates for entry into a company wide project scheduling process.

WORK ENVIRONMENT:

o Duties for this position are normally conducted in an office environment. Our Engineering office is an integral part of the entire production facility including fabrication, purchasing, inventory and assembly. Interaction with all these departments is required.
o During the engineering duration of the project, visits to the customer site may be required for the verification of customer details, development of concepts and project approvals.
o During fabrication and assembly phases of the projects, the work environment will include interaction with staff in the associated shops.
o Following shipment, travel to customer site is sometimes required to assist during installation, testing, commissioning and start-up.

TRAVEL:

o Project Engineers typically travel 10-20% of the time with 95% of the travel within the United States. We supply equipment around the world with international focus in Europe, Japan, Australia and Canada.

JOB DETAILS:

o Position is a salaried position
o Overtime, if required based on schedule, is unpaid.
o Full benefits package including medical, prescription, dental and vision plan available.
o 401(k) retirement plan available.
o Life and Long Term Disability insurance.
o Normal work hours are M-F 7:30AM – 4:30PM (1 hour lunch)

Space utilization is a huge concern for most factories. One of our customers needed to single file frozen food trays after coming out of a freezer 20′ in the air. He barely had room for the spiral conveyor to get them down, and he didn’t know how to get them in a single file to feed the wrapper. We partnered with Ryson spiral conveyors to build a 3D Infinity table around the spiral.

It sets the proper elevation, single files the trays, and buffers against downtime in a small footprint. What should we call this magnificent beast? The Ry-Finity? The Magic Frozen Food Dispenser? The Awesome Tray Vortex? The Swirly? Ok, maybe not the Swirly.

You might also want to check out Ryson’s blog.

MTR stands for Mean Time to Repair.

In automated processing and packaging lines, Mean Time to Repair is the average time it takes to repair a machine once it malfunctions. It’s used to calculate how much buffering is required upstream or downstream. If your line’s longest MTR is 3 minutes, then you need at 3 minutes of accumulation.

Wait, but doesn’t that mean I will only be able to buffer against half the downtimes? If you have an even distribution of downtime durations, then yes, you’d only buffer against half the downtimes. What we see in reality is that most packaging machinery has a high number of very short downtimes (under 3 minutes) and a small number of very long downtimes (10-60 minutes). Here’s some representative (but fabricated) sample data to illustrate this point.

The MTR on this machine is 3.76 minutes. A 3 minute buffer would cover 92% of all downtimes on this machine. What would be the machine and facilities cost of capturing that last 8%?

How do I reduce MTR?
MTR is made up of three components: Knowing, Finding, and Fixing. You must reduce one of these three to reduce MTR.

Knowing: The time it takes for anyone to realize the machine has malfunctioned and requires human intervention. The ways to reduce this component are by adding alerts (light stacks, alarms) or operators to continually watch the equipment.

Finding: The time it takes for someone to find out what the problem is. This step can be reduced by programming helpful error messages into the machine’s HMI that tell you exactly where the problem is. Modern photocopiers do this by telling you where the likely jam points are. When training operators, make sure they know what the most common malfunction reasons are so they can check those areas first.

Fixing:: The time it takes to actually fix this problem. Reducing this step is the hardest and most difficult to change once a machine is installed. Hopefully this has been thought about and discussed during the design phase of the equipment. Machines that are easy to repair must start and stop gracefully, have disconnects easily within reach, accessible doors and guarding, and easily explained repair instructions.

In many cases, the first two steps take far longer than the third so there is a lot of room for improvement. Reducing MTR helps keep your line running efficiently and allow you to tolerate more frequent hiccups in production.

Update: I recently made some changes to this article. Most assumed that I was in favor of always slowing down to increase throughput, but it’s actually only advisable if you can increase efficiency by a significant amount (10-20%). All the changes are in the last paragraph.

Can you increase efficiency and throughput by slowing down?

I recently had a discussion with a customer and an engineering firm about increasing throughput by slowing down the rate of a labeler from 400/minute to 380/minute. They recorded an improvement in efficiency to justify the change.  I questioned the decision from a thruput standpoint and wanted to come up with a good way to determine if an increase in efficiency actually increased the thruput or not.

Is slower better?

Efficiency is calculated using the following formula:

MTBF / (MTBF + MTR)

MTR = Mean Time to Repair
MTBF = Mean Time Between Failure

A properly buffered line should have capacity to handle the longest MTR on the line. The difference in maximum rates should be such that the table can go from full to empty in less time than the MTBF. For example, if you have a line like this:

Your labeler must have a MTR of 3 minutes or less and an MTBF of 9.9 minutes or more, giving us a minimum labeler efficiency of 77%. So what if I decrease my max rate in an effort to improve efficiency?

My minimum required MTR is the same since I’m still filling the buffer at 330 bpm, but my minimum required MTBF is now 19.8 minutes. This gives us a way to measure whether the decrease in rate has affected throughput. My labeler efficiency must now remain above 87% (19.8 / (3+19.8)) to keep the filler running and maintain throughput.

As the labeler slows down, its efficiency must go up to maintain throughput for the packaging line.

The formula can even more simply be expressed like this:

e = (Fr / Lr)

Where e = the minimum efficiency needed to maintain throughput
Fr = the max rate of the constraint
Lr = the max rate of the machine in question

If I run the labeler at 400 bpm I need to maintain a labeler efficiency of 77%. If I run it at 380bpm, I must maintain an efficiency of 87%. So if slowing the max rate of the labeler resulted in improving the efficiency from under 77% to something over 87%, then yes it will have improved throughput. If they were already running above 77% prior to the rate change, then throughput will be unchanged. If efficiency is under 87% after the rate change, then throughput will decrease.

In practice you have to find the right balance between rate and efficiency. It may be tremendously more difficult to maintain 87% than 77%, due to inconsistent materials or operator error.

Business books come in three types: Great, bad, and awful. Here are my favorites.

The Goal by Eli Goldratt

The Goal by Eli Goldratt: Classic novel about the theory of constraints. I didn’t understand my job until I read this book.

Getting Things Done by David Allen: Read this book if you want to complete projects that have been lingering for years and be productive despite everyday distractions. Can’t recommend it enough.

The Visual Display of Quantitative Information by Edward Tufte: There’s a science to making great charts and graphs and this is the textbook. If you make charts for your job, you absolutely have to read this. See our results.

Priceless by William Poundstone: Before switching to Computer Science I toyed with being an Economics major in college. It’s a fascinating science and helps explain many things in the world. This book helped me understand that when it comes to price, throw economics out the window because psychology is everything.

The Long Tail by Chris Anderson: 20th century mass market products were about producing hits. Distribution and production costs have sunk so low, it’s now about producing anything for anyone. Does this book apply to our business? The constant stream of custom quote requests says yes.

The Toyota Way by Jeffery Liker: The Toyota Production system changed world wide manufacturing and this is probably the best written example of what it is.

The Wisdom of Crowds by James Surowieki: Polls are almost always right and committees are usually wrong. This book explains why.

Rework by Jason Fried and David Heinemeier Hansson: A takedown of standard business practices and ideas for new companies.

Any suggestions?

We have a Garvey twitter account, but I mostly use it for internal communications (read this for an explanation). I spend much more time and effort on my personal twitter account trying to engage customers and the industry right along side friends and strangers. I think the only way social media can benefit our business is by participating as a human being and not a company. PMMI’s Michael Hess put together this video to show how they’re utilizing social media and enhancing our own social media efforts.

So far Twitter has been a fun distraction during the show and has gotten us some free press as an early adopter. It will be interesting to see how it will be used during Pack Expo in Chicago this year.

The best social media mavens aren’t robots spouting their company press releases. They post about whatever interests them and occasionally comment on industry news and events. It should go without saying that their posts may not always represent the views of their respective companies, but I’ll say it anyway. Here are some great industry tweeters:

PMMI
The Packaging Diva
Jake Garvey, Garvey Corporation
Michael Senske, Pearson Packaging
Mike Collins, Federal Mfg Co.
Kate Putnam, Package Machinery Company
Steve Windham, Omron
Marc Ostertag, B&R Automation

My entire packaging list.

Which dry lubrication is the best?

Traditionally, beverage bottlers lubricate their conveyors with soap and water systems to prevent bottles from tipping over and extend the life of their wearstrips. With an eye on cost savings and sustainability, bottlers have been replacing these systems with “dry” lubricants that perform the same function, saving a tremendous amount of water. Most dry lubricants used for bottling aren’t actually dry, but are highly concentrated and stay on the chain surface for long periods of time. All of them were pretty good, and most dry lubricants even outperform soap and water lubes by a significant margin.

We’ve done a side by side comparison of several commercially available dry lubes with an eye on two factors:

1. How much do they reduce the friction between the conveyor and the product?
2. How clean is the lubrication? How much build of gunk and dirt do we see over time?

We’ve ranked six dry lube brands by this criteria and here are the results.

Friction Reduction Ranking

1. ICC’s Dry Traxx
2. Johnson Diversey’s Dry Tech V
3. Hartness DCL
4. Drylube.co.uk
5. Ecolabs DryExx
6. SKF
7. No lube (control group)

Head to head lube test conveyor

Our testing methodology was simple.  We created a multi-lane conveyor that we could raise up on one side, which created an incline.  We slowly lifted one side of the conveyor and saw which of the products started sliding back first.   Here are some important notes we took from our comparison:

1. For this test we used PET beverage bottles.
2. PTFE based lubricants (ICC, Johnson Diversey, and Hartness) strongly outperformed the silicone based lubes in reducing the friction between conveyor chain and PET bottles
3. The conveyor chains used in the test were Rexnord Platinum Series (PS) 770.
4. The tests were conducted over 110 minutes of run time
5. 3ml of each lubrication was used on each chain.
6. Three separate tests were performed

Sanitation Ranking

1. Drylube.co.uk
2. Ecolabs DryExx
3. ICC’s Dry Traxx
4. Johnson Diversey’s Dry Tech V
5. Hartness DCL
6. SKF

When looking at sanitation issues, we looked for what the chain and product looked like after a few hours of run time.   Was there dust or dirt build up?  Did we see any waxy or gooey build up in the knuckles of the chain? Here are some notes we took from the cleanliness comparison.

1. Drylube.co.uk, EcoLabs, and ICC strongly outperformed the others in this category.
2. The EcoLabs and DryLube.co.uk lubrication may have completely dried off during the 110 minute test.

ICC's Dry Traxx RTU is our recommended dry lubrication

We hope this comparison helps your company make their decision about which lubrication is best for you.  Out of all the lubrications we’ve seen, we recommend ICC’s Dry Traxx RTU.  It’s the best balance of performance and cleanliness and it’s also rated H1 and H2 for food contact.

For additional questions about dry lube or for a quote on a dry lube application system for a new or existing conveyor system, contact us today. All we need to know is the number of lubrication points.

Join us at Interphex in New York City April 20-22 at the Jacob Javits Convention Center.  We’ll be showing off our Infinity Rx vial handling technology where we can accumulate and single file the tiniest of vials.

We are often asked for recommended speed settings for our conveyors and accumulation tables. Here are some handy formulas to use for converting product rates to chain speeds and the frequencies of the variable frequency drives (VFDs) that power them.

This formula converts products per minute (ppm) to feet per minute (fpm) for a simple conveyor:

d * r * 1.1 = c

d = Product diameter (ft)
r = Desired product rate (products per minute)
c = Conveyor speed (fpm)

The 1.1 modifier is to overcome a shallow angle in a side transfer from one conveyor to the next. This may be more or less depending on the angle and the type of the transfer.

This formula converts products per minute (ppm) to feet per minute (fpm) for Bi Flo Accumulation tables and Infinity Accumulation tables:

d * r * 1.5 = Bc
d * r * 1.25 = Ic

Bc = Bi Flo conveyor speed (fpm)
Ic = Infinity conveyor speed (fpm)

The modifiers (1.5 and 1.25) may vary depending on how steep the outfeed guides are, but these are the most common starting points.

Shaft mounted gear reducers. That's me on the right.

There are a lot more variables to consider when converting the speed of a conveyor to the Hertz on a VFD. You need to calculate the revolutions per minute of the drive shaft. Sometimes this is given on the faceplate of the gearmotor as “Out RPMs” or “Shaft RPMs.” If not, the gearbox will have a ratio on it (10:1, 20:1, 60:1, etc.) and the motor will list how many RPMs it makes at its standard voltage (typically 60Hz). The conveyor pitch is the length of each link in the modular belt that engages one tooth of the drive sprocket. If the gearbox is mounted right on the drive shaft, it is called a shaft mounted motor and there is only one point of reduction. If there is a drive chain between the gearbox and the conveyor drive shaft (base mounted motor), there is an additional point of gear reduction in the ratio of the drive and driven sprockets on the drive chain:

60 * ( s / ( (p * t * v) )) = h
m / g / b = v


s = Conveyor speed (fpm)
p = Conveyor chain pitch
t = Teeth of the conveyor drive sprocket
v = Conveyor drift shaft RPMs at 60Hz
h = Frequency of VFD at desired conveyor speed (Hz)
m = Motor RPMs at 60Hz
g = Gearbox ratio
b = Ratio of drive to driven sprockets on base mounted systems

Basemounted drive system. The motor is mounted underneath and the drive chain is covered by the rounded guard on the left.

For example:
Desired conveyor speed: 84fpm
Chain pitch: 1.5″
# of teeth on conveyor drive sprocket: 16
Motor RPMs at 60Hz: 1700
Gearbox ratio: 30:1
Drive sprocket for base mount: 20 teeth
Driven sprocket for base mount: 24 teeth

(84 / ( (1.5" / 12") * 16 * (1700 / 30 / (24/20) ) ) * 60 = 53.3 Hz

Variable Frequency Drives (VFDs) control the frequency of the power being sent to the motor. This allows a control system to change the conveyor speeds based on line conditions.

So to get REALLY crazy and go all the way from product rate to the frequency coming out of the VFD, we use this for an Infinity Accumulation table:
60 * ((d * 1.25) / ( (p * t * (m / g / b) ) )) = h

Bi Flo Accumulation table:
60 * ((d * 1.5) / ( (p * t * (m / g / b) ) )) = h