Mini Case: JAFI Donuts (JAFI)

Dewey Johnson sat in his office contemplating the past year of operation of his JAFI Donuts (JAFI) shop. JAFI served walk-in customers, and also made donuts to be stocked at local grocery stores and coffee shops. Over the past year, Johnson had spent considerable time trying to increase sales but had not spent much time focused on the operations of the shop. Through his window, he could see the line for donuts extending well into the parking lot. While he was pleased with the results of his sales push, he realized he needed to assess his capacity and maybe consider expansion.

Product Sales

Donut production at JAFI was currently limited to a single 8-hr shift per day, 7 days per week. During peak hours, Johnson maintained a staff of 3 to 4 employees that was more that capable of running the highly automated process without any additional slowdown. Currently Johnson sold, on average, 1100 dozen donuts per day of all varieties. The standard batch sizethat he had instructed his employees to use was 8 lb.

The Production Process

The donut-making process consisted of four stages: (1) batching), (2) mixing, (3) production, and (4) customization.

The batching stage started with an operator combining all the ingredients in a mixing bowl. Water was added first, followed by all of the dry ingredients contained in JAFI's proprietary donut recipe. It took 2 minutes to place the ingredients in the mixing bowl. The equipment could handle batches of dough of various sizes ranging from just 2 lb. to 20 lb. Each donut required exactly 2 oz. of dough (1 lb. = 16 oz.).

After the batching stage, the batch was placed in the mixer. The mixing process took 2.5 minutes per batch, and the mixer turned off automatically at the end of the process.

The production stage consisted of three steps: extruding, frying, and glazing.

After the mixing stage finished, the dough was transferred into the extrusion machine container. There, the dough was pushed through cylindrical cutting attachments (cutters) that extruded the dough into individual pieces that would eventually be turned into the finished donut. The machine used a set of 3 cutters. Each cutter could extrude dough at a rate of 18 extrusions per minute. Therefore, using 3 cutters, the machine-made donuts at a rate of 54 donuts per minute. This machine had to be set up before each batch was extruded. This included cleaning the machine from the previous batch, cleaning the cutters, and adding the fresh batch of dough. The setup took approximately 1.5 minute per batch.

During the extrusion stage, as soon as each donut was extruded, each donut was immediately dropped directly into hot shortening in a long and narrow fryer. The fryer ran continuously and had sufficient space to handle as many donuts as the extrusion machine provided. Each donut stayed in the fryer for 90 seconds. Surface rods pushed the donuts through the fryer.

During the frying stage, as soon as each donut was fried, each donut was cooled on a conveyer for 45 seconds before passing through the glazing machine. The cooling conveyor and glazer also ran continuously and had sufficient space to handle as many donuts as the extrusion machine provided, so finished donuts were produced at the rate at which they were made by the extrusion machine.

After the cooling/glazing stage finished, in the customizing stage, donuts were customized to either be placed for sale at the counter or boxed for specific customer orders. This step involved adding a range of different toppings- from traditional toppings like sprinkles to unique toppings such as Ellis Brother's world-famous pecan from right up the road. One employee handled the customization step. On average, the employee was able to customize two donuts every 3.5 seconds.

Johnson had noticed a disturbing trend. Each day, JAFI was turning away customers because it was unable to make enough donuts to meet demand. He needed to find a way to increase his capacity. One change Johnson is considering is to increase the batch size.

QUESTION 3.3. Calculate the maximum number of donuts that can be produced in an 8-hour workday (for maximum batch size is 20 lb.)then answers parts a to d below. Pay attention to the requested units of calculations.

a. How many donuts are made in the first batch of the 8-hour workday inunits of donuts?

b. How many minutes remain from the 8-hour workday after the time to make the first batch in units of minutes?

c. How many donuts can be made after the first batch during the remaining 8-hour workday in units of donuts?

d. What is the total number of donuts made in the 8-hour workday inunits of donuts?