In any warehouse, order picking – the function of retrieving goods from their racking locations is one of the most labour-intensive and costly activities, with about 55% of warehouse resources going towards this single activity. Currently, with intense competition, manufacturing companies are under pressure to reduce operating costs and preserve profit margins. In this scenario, making order picking a cost-effective activity assumes a large role in the economical growth of a company.
Hence, it is crucial to take the holistic view and pay attention to factors affecting it, such as warehouse racking layout, picking methods, warehouse racking or shelving systems and rack zones.
Let us first take a look at the types of order picking:
Piece Picking: This is the most commonly used picking method wherein one order is picked one line at a time. In this style of picking, there are no scheduled orders and they may be picked at any time during the day.
Pros: It is simple and is useful for fast order fulfillment. It can be used for tracking the picker’s accuracy.
Cons: However, this method is not efficient as it involves high travel time for picking.
Zone Picking: In this method, pickers are assigned specific zones in the warehouse and they are responsible for picking all SKU’s from that zone only. Zone picking is ideal for situations wherein numerous orders come in at a time.
Pros: As pickers are assigned discrete zones, there is less interference with other pickers blocking aisles.
Cons: The method is not as efficient for warehouses where customer orders are infrequent or few in numbers.
Wave Picking: This is a combination of zone as well as batch picking. When several pickers move through the zones picking up orders only from those zones, they create a “wave” of simultaneous picking throughout the warehouse. This type of picking is more appropriate for warehouses with a great number of SKUs.
Pros: Since the individual sorting and consolidation is done later down the line, more items of similar size and shape can be picked up in one ‘wave’, enabling a faster process.
Cons: For all the downstream sorting into individual orders, equipment such as tilt-tray sorters may be necessary; this might be expensive, depending on the size and type of operations.
Batch Picking: In this system, multiple orders from the same product location are picked at the same time, minimizing repeat trips to each location. It is best used in situations where there is a dense concentration of SKUs over a large area.
Pros: It is time-saving. Also, as most batch-picked items are usually transported via carts, it is economical.
Cons: For large warehouses, it may result in overcrowding of carts with multiple pickers getting in each others’ zones.
In Europe, Japan and USA, automatic case picking (ACP) is common due to space and labour costs. ACP involves the use of robotics and other automated equipment. In this article, for the sake of clarity, we will focus on manual order picking.
The success of manual order picking depends on:
- Warehouse Storage Layout
- Existing picking arrangements (pallet racking, shelving, Case flow systems)
- Available order picking machinery (pick carts, trucks, pallet jacks)
Apart from above, we have listed down major considerations and ways to improve order picking efficiency in a warehouse.
- Devise efficient processes: The first step toward a productive order picking process is making sure that the picking-and-packing process is well documented and followed by way of clear SOPs (Standard Operating Procedures). Review and fine-tune the process periodically to further improve by eliminating inconsistencies. SOPs should ensure sufficient verification for each step in the process.
- Reduce travel time: The time taken by a picker to walk to different storage racking media in the warehouse (the pick line) can greatly influence the order picking efficiency. Reducing the walking distance not only makes the process faster, but also cuts down on errors caused due to fatigue in order pickers.
Some of the main things to do to reduce the distance for order picking are:
- Picking from both sides of the aisle
- Picking multiple orders in a single trip (aka batch picking or cluster picking)
- Stocking slow-moving items on inside/deeper aisles
- Introducing conveyance systems
- Use appropriate storage systems: Using the right kind of racking for storage in a warehouse affects the efficiency of the picking operations. For example, slow-moving items are better stored in bins on shelves, whereas faster-moving SKUs should be placed in pallet racks.
- Implement slotting for warehouse racks: The system of grouping similar kinds of inventory in a given storage racking space is called slotting. Items can be slotted together on the basis of size, velocity, clubbing, seasonality, etc. Surprisingly, studies show incorrect slotting in a typical warehouse, can result up to 20% reduction in picking efficiency. Time and motion experiments have noted that correct racks slotting can reduce errors and the time taken for picking by increasing the stock visibility and ease. With a little effort, proper slotting can be maintained at all times for optimized order picking efficiency.
- Maximize floor level material storage: It is a known fact that order picking at ground level is more productive than that at higher levels. But, the challenges is warehouses have limited space to store at ground level. One way around this problem is to stock fast-moving SKUs at floor level and low levels and keeping slow-moving ones at higher levels.
- Create Hot Zones: Picking from more pick locations at a time, i.e. a higher pick (or hit) density results in higher warehouse productivity. Therefore, it is a good idea to set up ‘Hot Zones’ consisting of fast-moving items that generate most of the picking activity in the warehouse. Applying the pareto principle of 80/20 here can be particularly useful. Store together the 20% of SKUs that comprise 80% of the total number of orders.
- Reduce changeover time: Operational studies have demonstrated that almost 20% of an order picker’s time is possibly spent changing from one assignment to another during his shift. This unproductive time should be eliminated as much as possible (e.g. by having quick access to unfilled pallets so as to eliminate walking long distances just to pick up pallets).
- Design ergonomic pick areas: Every pick location that is just a bit out of reach adds a little extra time to the order line. In the long run, this adds up and can lead to up to 5% reduction in order picking productivity and also higher error rates. Having ergonomically well-designed pick areas will thus add to the speed of the picking process.
- Invest in training: Experts agree that efficient warehouse operations – including order picking – are a function of great team effort. To this end, regular training and quality checks for warehouse operators is a critical activity. Training pickers in using the most suitable and energy-efficient methods of order picking and packing will save crucial time and money. The monetary savings can be routed back to the pickers in the form of incentives for efficiency and speed. In the long run, these initiatives can reap rich dividends.
Conclusion:
Efficiency in order picking is critical to warehousing operations as it determines throughput rates and order fulfilment and service levels. It also plays a fundamental role in ensuring customer satisfaction and the smooth, uninterrupted run of the logistics operations.
Especially, with concepts such as next-day and same-day deliveries becoming more and more common for major manufacturers and e-tailers, the speed and efficiency of order picking has assumed extremely high significance. Every second can mean the difference between a promised delivery on time, or not.
Hence, efficient and streamlined order picking is one of the most important functions in warehouse operations and needs to be reviewed and revised periodically for optimum performance.
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Warehouse Storage Layouts, Warehouse Optimization, Warehouse Operations
