Pack Phase – Judge, Jury and Executioner?

Background

You may have heard the old phrase where someone was described as being the “judge, jury and executioner.” Its definition per Wikipedia:

1.    (idiomatic) Someone with the roles of judge, jury and executioner;
someone with full power to judge and punish others unilaterally.

This phrase is used to describe one person or entity as being completely in control over another’s fate – a sole body yielding the power and authority to determine another’s outcome. In injection molding, the PACK portion of plastic injection is often overlooked, but it has the power to control so much – typically more than is often realized.

It has been decades since the injection molding industry underwent a significant and very positive growth in machine and process capabilities. Anymore, at a minimum, two injection stages should be used when molding properly. This 2-stage filling of the mold begins using a constant and typically fast fill rate (FILL) followed by the remainder of fill being completed under constant pressure for a period of time – the very definition of the V►P (velocity to pressure) transfer on your injection molding machines (IMM). Processing this way is called by many names with the most popular being referred to as scientific injection molding or decoupled molding.

Under 2-stage molding, this stage of injection, aside from being called 2^nd stage, is commonly referred to as HOLD, PACK, or PACK and HOLD. Even though multiple things are being accomplished, this PACK and HOLD stage is typically a shared set of machine parameters. After V►P, the 2^nd stage begins with the final filling of the mold cavity and then the pressurization (or compression) of plastic into the mold cavity – these two things equal the PACK only portion of 2^nd stage injection. Next, and without any machine setpoint transition, the true HOLD phase begins. HOLD maintains this 2^nd stage plastic pressure setting to help compensate for some of the plastic shrinkage that occurs from the molten plastic solidifying and cooling in the cavity. This continues for a set period of time until the gate has solidified at which point the screw may then be programmed to rotate to prepare the next shot of plastic. It is important to note that as a single setpoint, the 2^nd stage pressure is only set to what gives the best balance for many items – filling the part without flashing, yielding the best dimensional results, and more.

3-Stage Injection for Immediate Improvements

Flash, short shots, and dimensional repeatability are some of the most common injection molded part quality issues regularly faced by an injection molder and mold maker. From the tooling side, flash can be the result of poor tooling condition, design and construction (i.e., where flash is present even when intentionally molding a short shot); however, the machine process settings play a very important role with regards to flash as well. So how can we better control our process to help improve upon these everyday issues?

PACK is arguably the most critical stage in an injection molding process, yet it is often combined and “along for the ride” with the HOLD stage. As it would be under any 2-stage injection process, PACK and HOLD are set as one occurring after the V►P transfer. With constant pressure (P) being the control for any injection occurring after this transfer, it is performed with far less control what any injection occurring under constant velocity (V) prior to transfer.

Creating a 3-stage injection process from a 2-stage one means separating PACK into its own stage allowing for the three separate stages (FILL, PACK and HOLD) to each have their own distinct and individually optimized machine settings. The PACK stage now accurately performs the final filling of the mold cavity and establishes the amount of plastic to be compressed into the cavity through a slower, more controlled 2^nd injection stage. With PACK moved prior to V►P, its speed (V) and positioning are able to be managed properly. The third stage, HOLD, is now alone after V►P – after the critical quality concerns have been established and managed in process. HOLD is now only a set pressure (P) for a set period of time starting very near to where the final screw forward position will be (i.e., the cushion) doing its job to help maintain the degree of PACK until gate freeze is reached. When implemented properly, significant improvements to scrap, quality, and overall manufacturing efficiencies will be realized throughout your operation.

What’s the Catch?

This change does require another level of processing competency, but it is a much easier jump than making the leap to using in-cavity pressure sensors for control and monitoring of your processes using expensive RJG or Kistler types of technologies. And this change is relatively free. We are heavily invested in the use of in-cavity sensors at Matrix; their merits are well-proven for the high-precision tight-tolerance products we make, but please know you can still make large gains by only investing in the training of your people. This is a “no-brainer” ROI if ever there was one in injection molding, since no large capital expenditure is required.

Matrix received an older, worn transfer mold that had always used a 2-stage injection process. We elected to have this mold serve as our test subject – an imperfect mold to serve as an example to clearly illustrate the differences between 2-stage injection and 3-stage injection. Our experiment on this worn 8-cavity electrical connector mold was performed in our oldest – but still quite capable – 120-ton injection molding machine. I asked our lead process engineer to establish his best 2-stage injection process; as an experienced, degreed plastics engineer who excelled at processing, he set a fundamentally sound process for this tool. We saved shots for evaluation. His process was then adjusted only to separate PACK from HOLD – optimizing each one individually – all of which took between 5-10 minutes. Shots from this 3-stage advanced injection molding process were also saved for evaluation.

Results

The results in our example showed significant improvements from the 3-stage injection process in every measured category. Critical dimensions between circuits in the X and Y directions as well as part flatness were improved by 50%. A limiting factor was that this part had worn steel resulting in excessive flash in the mold’s non-critical void coring areas, something we later rectified in tooling for our customer. As-is, however, parts from the improved process with the highly controlled PACK phase exhibited a flash reduction of nearly 50%. Part weight increased by 0.5%, a significant increase for a thin-walled connector part already exhibiting excessive flash. The increased control allowed for improved pack resulting in a heavier part than before. The denser part shrunk less, and therefore warped less, providing greater dimensional accuracy and stability. Process monitoring over time would have showed the 3-stage process to have less variability and therefore more consistent part quality as well.

Often overlooked, this real-world example shows how the PACK portion of injection holds so much importance and relevance to the quality of molded parts. PACK has the ability to significantly affect the molded product’s outcome with regards to flash, dimensional accuracy and repeatability, and more. Moving forward, this ideological change may be the low hanging fruit that provides immediate and relatively pain-free improvements to your metrics while reducing unnecessary waste in your operation. Your machines are capable, and it isn’t quite the leap you may think it is to implement. I’ve been establishing all processes in this manner for nearly 30 years, and I have yet to find a reason to not start with a 3-stage process and make adjustments from there. Why settle when better is free for the taking and best is a slight process change away?

Tom Moyak

Director of Business and Engineering Development

Matrix Tool, Inc.

4976 Franklin Road

Fairview, PA 16415

USA

www.matrixtoolinc.com

814-474-5531

About The Author: Tom Moyak is a plastics professional with over 30 years of diverse engineering and manufacturing experience who takes pride in achieving significant increases in quality, efficiency, and profitability through the development of innovative tooling and molding solutions rooted in fundamentals.

Tips on Effectively Using Yard Signs

We have all seen them, small signs sticking up out of the ground announcing a sale or advertising a service or business. Why in this digital age do we still see yard signs everywhere? It’s simple the idea of yard sign marketing is to grab your attention while out in public. Think about it, have you ever gone to a yard sale or tried a new burger place because you saw a sign while driving or walking down a street.

Most of us react to new stimulus when we are outside of our home or office, when something sticks out and makes an offer that is intriguing it makes us react. Yard signs are not a replacement for digital marketing, radio, or television but then that is not the audience they are going after. Yards signs are to gain the attention of someone here and now. It gets your attention and possibly (if its something you like or are looking for) gets you to act now! There are a lot of assumptions about effectiveness, is it something people are interested, does it offer something I want now, do I have time to stop. But for many, the answer is yes.

So, the concept is to grab someone’s attention and offer them something they would like now. It is important that your yard sign stands out, gets your message out quickly and powerfully, and is easy to read. The biggest mistake people make is trying to put too much information on a sign and using small fonts for your message. A typical yard sign is 18x24” and is the size of a postage stamp to the driver 20-50 feet away. Bright contrasting colors on the background and lettering help the sign stick out from its surroundings. Don’t use muted earth tones on a lawn or tree lined street, you’re trying to get someone’s attention does not blend in with the surroundings.

Thick Simple Message

Font Type, Size and Stroke Thickness all combine to make the words stand out and make the sign easy to read, especially from a distance. Don’t crowd the sign with a lot of text, leave space about the message, phone number and logo so that it again stands out and is clearly readable to your potential audience. Sign messages need to be simple but effective, “WE’RE HIRING” “SALE” “50% OFF” are words that are easily recognized. Web addresses or Facebook addresses are usually too long and need smaller text besides, you want the customer now not when they get home.

Where You Put Them

Finally, is sign positioning, make sure the sign stands out, clear from other distractions like trees, parked cars, or tall weeds. Use your background as a way to frame your advertising message. You will also need to secure the sign to the ground with a wire frame or heavy-duty yard sign stake to keep it from blowing around. You may have to order these separate from the actual signs. Look for sturdy construction, this will help anchor the sign better to the ground and can be re-used for other promotion signs in the future. Look at the thickness and construction of the stakes as it is well worth getting a quality stake that works over seeing your signs knocked to the ground.

Neal Rabogliatti, President, DMS Strategies, www.digitalmarketingstrategiesllc.com

Industrial Wire Baskets - Which One Is The Right One?

The humble industrial wire basket came into existence in the 1890s to help manufacturers move heavy bulk parts easily and efficiently. Over the years baskets became the choice for companies that made stampings, castings, and machined parts because they offer a durable reusable container that can withstand the abuse in a manufacturing plant.

Benefits:

• Strong construction enables them to handle the loading and unloading of heavy parts.
• The mesh sides allow liquids (like cleaners or degreasers) to freely flow through the basket and parts and drain easily making operations for parts cleaning more efficient.
• The open design allows for easy identification of parts inside or for inventory management.
• The heavy steel construction means they can be reused and subjected to a variety of elements time and time again with needing replacement.
• The ridged construction allows them to be stacked safety and to reduce valuable floor space.
• Being made of steel, they allow parts to be heat treated within the container reducing the time to load and upload parts in the process.

What should you look for when buying industrial wire baskets?

This will depend on what type of parts you want to store or move. Not all baskets are the same, in fact there are many options on the market and buying solely on price may not be the best plan.

Strength

For heavy, sharp edge parts you need a basket strong enough to withstand the weight and capacity you want. Cheaper thinner wire basket may save some money but are useless if your product causes the sides to bow outward. Be careful about buying collapsible wire baskets for heavier parts, the design allows them to take up less space when not in use, but most don’t offer the integrity for handling large heavy parts.

Stackable

Space is usually a valuable commodity in a manufacturing plant or warehouse, and baskets can take up a lot of space, that’s why the ability to stack baskets is so important. You need to choose a wire basket that is rigid and strong enough to hold the weight of other baskets on top as well as the capacity and weight of the parts inside. Again, rigid frame baskets offer more strength for stacking than collapsible.

How they are welded

The strength of the frame and mesh sides is important but so is how they are held together. You want to look for wire baskets that are “Weld to Print” and not “Stitch Welded”. Weld to print means the welded seam is a continuous bead from point to point as designated in the design print. Many companies in an effort to reduce costs stitch weld the parts together meaning the weld seams are a series of small welds to secure the seam rather than a continuous one. This shortcut can significantly reduce the integrity of the entire basket because the parts weight or shifting can compromise the weld points and cause the entire basket to break apart resulting in damaged product or worse employee safety.

Size and Capacity

There are many options in the market when it comes to sizes, It is important to determine two factors regarding size when purchasing. First is the size of the parts and the capacity needed to be stored to transported, the inside size. You also must determine the outside size or “footprint” the basket creates so that it can be stored or moved inside your facility easily and not create problems of being too large. You may want to directly contact a metal fabricator to have a basket made to your dimensions and capacities to save money and time in the long run. Once you determine the size and capacity needed, make sure the basket has the strength to handle your parts so that your basket doesn’t break apart or need to be replaced more often.

ESCP

ESCP is a contract metal fabricator located in Davenport, Iowa. They have built their business on fabricating custom industrial wire baskets, storage racks and shipping containers. They work with your prints or have the relationship with a design agency to design the prints for a custom basket. They have developed a reputation for quality workmanship and manufacture baskets to many OEMs across the country.

Many Thanks to John Nelson from ESCP for providing the information for this post.

ESCP - www.escp.net

Do Indoor Grow Lights Work?

Like most answers, it depends! Plants need light for photosynthesis and in theory a standard fluorescent bulb will help plants grow, just not very much and not very efficiently. There are a wide range of grow light types that help plants to grow but most have their pros and cons.

Light & Photosynthesis:

All plants contain proteins called light-harvesting complexes, or LHCs. When light reaches a plant  it excites the LHC which in turn excites other LHC receptors and eventually reaches a reaction center in the plant. The reaction center creates a chemical reaction to convert water into oxygen gas and positively charged particles called protons. The photons trigger the production of enzymes that create energy in the form of carbohydrates which feed the plants metabolism.

But the reason sunlight is so effective is because of several components that directly affect photosynthesis. Sunlight contains a wide spectrum of wavelengths ranging from 100 nm to 1 mm, which include ultraviolet, visible, and infrared radiation. Simply put, a spectrum is characterized by a color range from violet to red. Plants require different color spectrums during different times in their growing cycle. Once a seed germinates it becomes a seedling and the vegetative phase of growth starts, it then needs light with a spectrum in the blue range to best convert light into energy to grow and become strong. After completing the vegetative phase, it needs to produce flowers and seeds called the flowering stage, at this point the plant needs a spectrum rich in red wavelengths to help produce buds and to flower and produce fruit and seeds.

Light’s intensity is another factor important to growing, wavelengths need to be delivered to the surface of the plant strong enough to promote photosynthesis. If the light is week or too strong, then the plant will react accordingly.

Finally, there is UV “Ultraviolet “and IR “Infrared” waves that help inform the plant to create certain defenses or strengthen a specific type of growth to better handle the environment. UV light helps lights to strengthen their defense against certain pests and UV light also help eliminate problems like mold.

So, the long answer is Yes, Grow Lights do help pants to grow but only ones that can mimic sunlight and provide a broad spectrum of intense light including blue and red light as well as UV and IR wavelengths.

Grow Light Types:

The traditional lights used were HPS “High Pressure Sodium” which did provide red light and good intensity, the problem is that they did provide much blue light and the intensity could be strong and the last factor, they are not inexpensive and require a lot of energy to operate.

LED lights became popular because they could also provide red spectrum light and ran much cooler and inexpensively over traditional HPS lights. New studies are showing however that they lack the UV and IR wavelengths which result plants needing other methods to ward off mold, pets, and some diseases. Some recent studies have show that the plants are not as large or productive as when grown with more intense light. LED lights are also very expensive to purchase, and one needs to make sure they are buying high end units in order to get the desired effectiveness needed.

A Technology Breakthrough!

One technology not discussed was CMH lights, Ceramic Metal Halide grow lights. These offer both the intensity to safely grow plants and operate at a much lower costs than HPS and are cheaper to buy than LED lights. One of the only issues is the traditional CMH lights tend to provide more blue light rather than red light.

So, a company called gGRO  manufactures an indoor grow light that takes the intensity and effectiveness of a CMH light but ads features to better mimic sunlight. The first feature is having two different bulbs inside the fixture, one that produces light with more blue spectrum and the other to provide more red spectrum. These can be controlled to best suit the growing stage of the plant. The lights do emit both UV and IR wavelengths and can help plants to ward off diseases and pests. They have also engineered the lights to run more efficiently over HPS and reduce initial costs. They are even designed to run off of solar power to further reduce energy costs. This is the closest indoor grow light to sunlight providing a good balance of full spectrum light with intensity and energy efficient operation and provide a great alternative to growers looking for a quality effective grow light.

Maritime Steel Casting Production

The maritime and shipbuilding industries are vast users of steel castings, from small to large, simple to complex.  Almost all floating vessels utilize some application of a steel casting, including most US Navy & Coast Guard ships.  Structural hull pieces, such as stem bars, stern tubes, and rudder bearings, to machinery elements inducing clutches, capstans, wildcats, or basic functional components like mooring bits, bow chocks, or anchors are all steel castings.  They are greatly different in application, function, material, along with a wide range of testing and inspection requirements.

Required Expertise

Casting design can be very simple to very complex, hence, the greatest benefit for a casting application.  It takes the knowledge and expertise of a high-quality foundry to achieve complete success.  The castings used in the maritime industry serve a function to lift, move, steer, guide, and even protect the sailors and crews that work around them every day.  Producing these castings is not just molding, pouring, and shipping another component by the thousands.  They are typically custom-made, one-off casting designs that are produced infrequently.  Knowing the use, function, requirements, and needs of every casting and it’s customer is critical for the foundry to ensure complete satisfaction.

Operations for Producing Marine Castings

Steel casting production requires a variety of processes.  It starts with engineering & pattern making, followed by molding and pouring.  After cleaning and heat treatment, any nondestructive testing is completed and the casting can be sent for further processing, whether that be machining, welding, or assembly.  One key to success for customers is working with a foundry that is vertically integrated, incorporating as many, if not all, of these processes, monitoring quality and delivery throughout the entire scope of work.

Conclusion

Sourcing castings with a wide variety of applications, material types, nondestructive testing, and certification requirements can be a daunting task.  Having fundamental knowledge of the entire casting process is a must.  Working with an experienced foundry who can comprehend the needs and requirements of a customer will ultimately end with satisfied customers, high quality castings, delivered on time.

Author: Lisa Wertzbaugher, Sivyer Steel - Director of Sales | https://www.sivyersteel.com/