by Bob Coningsby, Apex Machine Company
These are significant questions that are deliberated when proposing the lowest possible unit cost system that will operate in an efficient and economical fashion. This can be determined quite easily provided that the molding machine, decorating system, assembly machine and packaging line are analyzed and assessed in every aspect of their feature and operation. Similarly, long-range goals and economic expenditure are critical factors that also should be considered in advance of the development and final confirmation of the project.
A 10-step analysis is suggested in order to truly verify the feasibility of an in-line operation.
Step 1. Molding
Step 1 involves the molding process, as certain molding processes are more conducive to an in-line operation than others. The five most common molding processes include thermoforming, rotational molding, extruding, blow molding and injection molding.
An in-line decorating process with a thermoformer is possible and practical; however, the key is volume, as large orders with limited changeovers should be run in-line with the thermoforming machine in an efficient and cost-effective fashion. Another variable to keep in mind is floor space, as an in-line process with a thermoformer requires space to allow a suitable buffer between the decorating system and thermoforming line.
B. Rotational Molding
An in-line process with a rotational molder also is possible, but because of the size of most rotational-molded parts, this is not a common practice.
Running in-line with an extruder is very common, but the key here is in the extruder itself and in the product being extruded. Some extruders and some products may not allow for either an efficient or practical interface.
D. Blow Molding
Running in-line with a blow molder is both recommended and highly suggested as most blow-molded parts take up air; hence, one cannot afford to handle the part twice prior to its subsequent shipment.
E. Injection Molding
Running in-line with an injection molder is highly recommended, but as with other molding processes, the key is volume.
In summary, running in-line with any of the processes mentioned is certainly feasible and, in many cases, practical. As a rule of thumb, Apex typically recommends running in-line only with blow molding or injection molding equipment, as both of these processes will allow for a better return on investment.
Step 2. Part Type
Is the molder producing a flat part, round part or odd-shaped part? Is a consistent part produced per the agreed upon tolerances? What raw material would be utilized and how big is the part being produced? All of these questions are extremely important when considering the potential of running in-line, as the part itself will in most cases dictate the resulting decision.
Flat and round parts are more ideally suited for in-line applications than odd-shaped parts, but the key is in the consistency of the part produced. An inconsistently made part will not allow for the use of specific technologies, which otherwise would be more conducive to an odd-shaped part.
Another factor to keep in mind is the size of the part and the material used to produce it, as some materials have different shrink characteristics than others. Certain materials also require pretreatment for particular decoration processes.
To summarize, smaller parts which are consistently manufactured are appropriate for an in-line decoration process. Before considering the idea of running in-line, the required graphics should be analyzed, as the type of artwork also will impact the feasibility of the decoration process.
Step 3. Volume
How many pieces per year will be produced? Will short runs or long runs be produced? How many cavities is the molding machine? Would that particular mold be dedicated to that particular molding machine? When running in-line, one must definitely take into account the volumes, as an in-line operation with a small-volume molding process may not be practical simply due to the cost of the automation.
Step 4. Artwork or Graphics
In most cases, the artwork required will dictate the decoration technology. Likewise, in most cases the decoration technology will impact the feasibility and possibility of running in-line. When evaluating the artwork or graphics, one must consider the location of the graphics as this too will dictate the decoration technology.
Does the round part need to be decorated for a full 360° circumference on the full length, or does it simply need to be spot printed? If a flat part is produced, would this require decoration on both sides, and would the graphics be applied to the full surface of both sides?
In producing an odd-shaped part, where do the graphics need to be placed? Would the part support itself during the decorating process? What type of artwork or graphics is needed? Would a one-color print be required or is multi-color artwork necessary? Is a metallic image needed or does the part require photo-style graphics? Would short runs or long runs be produced; and how often would the artwork or graphics change? All of the above are critical questions, as the style of graphics will dictate the decoration technology; and the decoration technology will determine the feasibility and practicality of running in-line.
Step 5. Decoration Methods or Processes
There are numerous ways to mark, decorate and apply graphics to a product, but for this article the focus will be on the most common technologies utilized today.
A. Pad Printing Pad printing is primarily used for odd-shaped parts and small volume applications. This process involves the utilization of a solvent-based ink, recessed printing plate and a silicon pad to achieve very high quality graphics on unusual surfaces or odd-shaped parts. Most pad printing machines operate in a reciprocal fashion and off-line, as the volumes are typically not large enough to justify the automation to interface the molding machine with the pad printing system.
There are continuous-motion pad printing machines on the market, and many of these systems do run in-line. However, the keys to an in-line operation with a rotary pad printer are the part – which in most cases is round – and the volumes. Large volumes will be needed to run with few changeovers to truly justify an in-line interface between an injection molding machine and a high-speed rotary pad printing system.
B. Hot Foil or Heat Transfer
Either process involves the utilization of a metallic foil or a preprinted foil which comes in contact with a heated surface to transfer the image to the substrate. Hot foil is suitable for small-volume applications where a semi-permanent metallic image is required. Heat transfer also is suitable for small-volume applications where a photo image is required as high quality graphics can be preprinted on the film.
As a rule of thumb, odd-shaped parts cannot be hot foiled or heat transferred; thus, most hot stamped or heat transferred parts are either round or flat. In addition, both technologies utilize a reciprocating part-handling motion, making it ideally suited for small-volume applications only.
In comparison to other technologies, heat transfer or hot stamp has an expensive per unit cost. However, this technology allows for a lower capital investment as heat transfer and hot foil systems are very inexpensive.
Silk screen machines are predominately used for one-color applications and for either round or flat parts. Some odd-shaped parts can be silk screened, but the printable area of the part needs to be round or flat, and consistently placed. As mentioned, silk screen machines only can apply one color at a time; however, there are numerous systems on the market today which can imprint multiple colors, assuming the order sizes are large.
As a rule of thumb, silk screen machines have a long changeover time, making a multi-color silk screen machine impractical to run in-line for small volume applications. On the other hand, if running in-line with a blow molding machine, a sufficient buffer can be incorporated between the molding machine and the print to run small orders. Again, the changeover time is extremely critical, as the buffer needs to allow for a sufficient part accumulation while a changeover takes place.
D. Offset and FlexApex Printing Processes
Most in-line applications involve the utilization of either the offset printing process or a FlexApex printing process. Both of these processes are designed for large-volume runs and allow for stop-and-start capability, which will occur in an in-line process. Both technologies require either a flat or round part; and a sufficient buffer is required to allow for an in-line color or artwork changeover.
E. In-Mold Label (IML)
IML only can be utilized with an injection molding machine. This technology is ideally suited for small-volume, high-quality graphics on either round or flat parts. Other shapes can be decorated with an IML, but the unit cost will be high and the cycle time will be low.
F. Laser and Inkjet
Both of these technologies are ideally suited for an in-line application where either variable data or a single-color artwork is required. Both technologies are non-contact, making them appropriate for almost any part type.
Preprinted sleeves are suitable for high-end graphics on blow molded parts and the automation required to operate in-line is both simple and cost-effective.
Step 6. Assembly Process
Does the product require a sub-assembly process – meaning, do other parts have to be attached to the part prior to its subsequent packaging and shipment to the customer? Some assembly processes can be done very easily in-line, but the more complex the part, the more difficult it is to run in-line. In addition, volumes need to be considered, as a high-volume, complex assembled parts would be more challenging to run in-line than a high-volume part that does not require any assembly at all.
Normally, an in-line application is not recommend for high-volume parts that requires multiple assemblies. The assemblies are the key, however. What parts have to be assembled to the decorated parts and do those parts also have to be manufactured in-line?
Step 7. Packaging Requirements
What type of packaging is required for the parts, and is the packaging of a simple or complex nature? How often would the package change, and how will the end package be shipped? These questions need to be addressed before considering the potential of running in-line with a molding process, decorating system, assembly machine and packaging line.
Packaging off-line is recommended because of the complexities normally associated with the packaging process. However, Apex currently is running numerous lines in-line with packaging, and once again, the decision is based on volumes.
Step 8. Automation to Interface
One of the most important factors to keep in mind when running in-line is the automation required to interface each of the machines within the line. Apex normally recommends a buffer between each system, but this is not a mandate, as many of our high-speed automated lines run completely in-line as the speed of each system is equally matched. Another very important concern when running in-line is the artwork and color changeovers. How often would colors and graphics change? If the artwork and colors need to be changed frequently, then Apex does not recommend running directly in-line, unless with a bowl feed and a buffer in between.
How long does it typically take to perform a changeover? The buffer needs to be larger or longer than the longest possible changeover timeframe, as it will not be affordable to stop the machinery when running in-line. Another key factor is machine efficiency, as an in-line operation will only be successful if each of the machines can operate in an efficient and non-stop process. If any of the machines which are part of this operation cannot operate efficiently, and each of the machines within this operation is not predictable, then Apex does not recommend running in-line.
Step 9. Cost
How much would an in-line operation cost, and would running in-line be affordable? From experience, this only can be answered with numbers, as the volumes will define the likelihood of a successful in-line process.
Step 10. Return on Investment
In order to justify running in-line, one must have a relatively appropriate return on investment. Apex typically strives for an 18-month payoff. Apex has been able to justify investment with a 2-year or 3-year payoff, but typically these are for programs which either have a longer life expectancy or a mandate for total automation. The medical industry is a perfect example, as many of the large volume medical products today must be run in-line as the process simply will not allow for an off-line mentality.
To summarize, Apex is a huge advocate of an in-line process, specifically in the U.S.; however, running in-line is not easy, and every aspect of the project must be carefully analyzed and assessed to truly define what is possible, practical and – of course – justified.
Bob Coningsby is CEO and chairman of Apex Machine Company. Apex serves every facet of industrial printing systems, custom printing systems and on-product printing, marking and decorating equipment. For more information, call 954.566.1572 or visit www.apexmachine.com.